Merhaba,
iOS üzerinde bir sözleşme onay uygulaması geliştiriyorum. Kullanıcıların dijital ortamda sözleşmeleri okuyup onaylaması gerekiyor. Ancak hukuki geçerlilik konusunda bazı tereddütlerim vardı.
Bursa’da yaşayan biri olarak bu konuda bir avukata danışmam gerekti. Şans eseri https://www.avukatcanata.com ile karşılaştım ve hem bireysel hem ticari sözleşmeler konusunda gerçekten çok net açıklamalar sundular. Özellikle elektronik imza ve KVKK uyumu hakkında verdikleri bilgiler sayesinde projemi yasal zemine oturtabildim.
Eğer bu tarz uygulamalar geliştiriyorsanız, mutlaka bir hukukçu görüşü alın. Yanlış bir adım size veya kullanıcınıza ciddi sonuçlar doğurabilir.
Teşekkürler 🍏
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I am trying to integrate Apple Music API using MusicKit and need to generate a Developer Token. However, when I try to create a new key from the Certificates, Identifiers & Profiles section, the “Media Services (MusicKit, ShazamKit, Apple Music Feed)” option is grayed out. We are getting the error 'there are no identifiers available that can be associated with the key.' Although we did checkmark 'musickit' in app services.
I have already:
Enrolled in the paid Apple Developer Program
Created a valid App ID under Identifiers
Logged in as the Account Holder
Tried multiple browsers and devices
Despite this, the option remains disabled. Could you please enable this or let me know what further steps I need to take?
Thank you!
Topic:
Developer Tools & Services
SubTopic:
General
Tags:
Apple Music API
Accounts
MusicKit
Developer Program
I regularly bump into folks confused by this issue, so I thought I’d collect my thoughts on the topic into a single (hopefully) coherent post.
If you have questions or comments, put them in a new thread here on the forums. Feel free to use whatever subtopic and tags that apply to your situation, but make sure to add the Debugging tag so that I see your thread go by.
Share and Enjoy
—
Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"
Testing and Debugging Code Running in the Background
I regularly see questions like this:
My background code works just fine in Xcode but fails when I download the app from the App Store.
or this:
… or fails when I run my app from the Home screen.
or this:
How do I step through my background code?
These suggest a fundamental misunderstanding of how the debugger interacts with iOS’s background execution model. The goal of this post is to explain that misunderstanding so that you can effectively test and debug background code.
Note The focus of this post is iOS. The advice here generally applies to any of iOS’s ‘child’ platforms, so iPadOS, tvOS, and so on. However, there will be some platform specific differences, especially on watchOS. This advice here doesn’t apply to macOS. It’s background execution model is completely different than the one used by iOS.
Understand the Fundamentals
The key point to note here is that the debugger prevents your app from suspending. This has important consequences for iOS’s background execution model. Normally:
iOS suspends your app when it’s in the background.
Once your app is suspended, it becomes eligible for termination. The most common reason for this is that the system wants to recover memory, but it can happen for various other reasons. For example, the system might terminate a suspended app in order to update it.
Under various circumstances your app can continue running after moving to the background. A great example of this is the continued processed task feature, introduced in iOS 26 beta.
Alternatively, your app can be resumed or relaunched in the background to perform some task. For example, the region monitor feature of Core Location can resume or relaunch your app in the background when the user enters or leaves a region.
If no app needs to be executing, the system can sleep the CPU.
None of this happens in the normal way if the debugger is attached to your app, and it’s vital that you take that into account when debugging code that runs in the background.
An Example of the Problem
For an example of how this can cause problems, imagine an app that uses an URLSession background session. A background session will resume or relaunch your app in the background when specific events happen. This involves two separate code paths:
If your app is suspended, the session resumes it in the background.
If your app is terminated, it relaunches it in the background.
Neither code path behaves normally if the debugger is attached. In the first case, the app never suspends, so the resume case isn’t properly exercised. Rather, your background session acts like it would if your app were in the foreground. Normally this doesn’t cause too many problems, so this isn’t a huge concern.
On the other hand, the second case is much more problematic. The debugger prevents your app from suspending, and hence from terminating, and thus you can’t exercise this code path at all.
Seek Framework-Specific Advice
The above is just an example, and there are likely other things to keep in mind when debugging background code for a specific framework. Consult the documentation for the framework you’re working with to see if it has specific advice.
Note For URLSession background sessions, check out Testing Background Session Code.
The rest of this post focuses on the general case, offering advice that applies to all frameworks that support background execution.
Run Your App Outside of Xcode
When debugging background execution, launch your app from the Home screen. For day-to-day development:
Run the app from Xcode in the normal way (Product > Run).
Stop it.
Run it again from the Home screen.
Alternatively, install a build from TestFlight. This accurately replicates the App Store install experience.
Write Code with Debugging in Mind
It’s obvious that, if you run the app without attaching the debugger, you won’t be able to use the debugger to debug it. Rather:
Extract the core logic of your code into libraries, and then write extensive unit tests for those libraries. You’ll be able to debug these unit tests with the debugger.
Add log points to help debug your integration with the system.
Treat your logging as a feature of your product. Carefully consider where to add log points and at what level to log. Check this logging code into your source code repository and ship it — or at least the bulk of it — as part of your final product. This logging will be super helpful when it comes to debugging problems that only show up in the field.
My general advice is that you use the system log for these log points. See Your Friend the System Log for lots of advice on that front.
One of the great features of the system log is that disabled log points are very cheap. In most cases it’s fine to leave these in your final product.
Attach and Detach
In some cases it really is helpful to debug with the debugger. One option here is to attach to your running app, debug a specific thing, and then detach from it. Specifically:
To attach to a running app, choose Debug > Attach to Process > YourAppName in Xcode.
To detach, choose Debug > Detach.
Understand Force Quit
iOS allows users to remove an app from the multitasking UI. This is commonly known as force quit, but that’s not a particularly accurate term:
The multitasking UI doesn’t show apps that are running, it shows apps that have been run by the user. The UI shows recently run apps regardless of whether they’re in the foreground, running in the background, suspended, or terminated. So, removing an app from the UI may not actually quit anything.
Removing an app sets a flag that prevents the app from being launched in the background. That flag gets cleared when the user next launches the app manually.
Note In some circumstances iOS will not honour this flag. The exact cases where this happens are not documented and have changed over time.
Keep these behaviours in mind as you debug your background execution code. For example, imagine you’re trying to test the URLSession background relaunch code path discussed above. If you force quit your app, you’ll never hit this code path because iOS won’t relaunch your app in the background. Rather, add a debug-only button that causes your app to call exit.
IMPORTANT This suggestion is for debugging only. Don’t include a Quit button in your final app! This is specifically proscribed by QA1561.
Alternatively, if you’re attached to your app with Xcode, simply choose Product > Stop. This is like calling exit; it has no impact on your app’s ability to run in the background.
Test With Various Background App Refresh Settings
iOS puts users in control of background execution via the options in Settings > General > Background App Refresh. Test how your app performs with the following settings:
Background app refresh turned off overall
Background app refresh turned on in general but turned off for your app
Background app refresh turned on in general and turned on for your app
IMPORTANT While these settings are labelled Background App Refresh, they affect subsystems other than background app refresh. Test all of these cases regardless of what specific background execution feature you’re using.
Test Realistic User Scenarios
In many cases you won’t be able to fully test background execution code at your desk. Rather, install a TestFlight build of your app and then use the device as a normal user would. For example:
To test Core Location background execution properly, actual leave your office and move around as a user might.
To test background app refresh, use your app regularly during the day and then put your device on charge at night.
Testing like this requires two things:
Patience
Good logging
The system log may be sufficient here, but you might need to investigate other logging solutions that are more appropriate for your product.
These testing challenges are why it’s critical that you have unit tests to exercise your core logic. It takes a lot of time to run integration tests like this, so you want to focus on integration issues. Before starting your integration tests, make sure that your unit tests have flushed out any bugs in your core logic.
Revision History
2025-08-12 Made various editorial changes.
2025-08-11 First posted.
Hey, I am using the terminal a lot. Since I updated to Sonoma (so, really a long time ago). My prompt or more precise the hostname always changes between three states. Sometimes it is username@Macbook-Pro-of-XXX, sometimes username@MacbookPro and sometimes it's username@xxxxxxxx-yyyy-zzzz-aaaa-bbbbbbbbbbbb. The latter is probably my UUID. Does anyone have a clue why this randomly changes?
Hi, I requested the https://itunes.apple.com/lookup?id=6482849843&country=us for getting the information of Goods puzzle sort challange , but the screenshotUrls in the response was empty. Is iTunes search API has issue with getting the screenshot urls ? Is there any plan to update it ?
Topic:
Developer Tools & Services
SubTopic:
General
Hi all,
I'm trying to integrate Apple’s DeviceCheck API into my Flutter iOS app. I already have everything set up on the backend — the Apple private key, key ID, team ID, and DeviceCheck capability. The backend is generating and signing the JWT correctly and making requests to Apple.
However, I’m currently stuck on the frontend (Flutter):
👉 How can I generate the device_token required by the DeviceCheck API (via DCDevice.generateToken) in a Flutter iOS app?
I understand that DCDevice.generateToken() must be called from native Swift code. I previously attempted to use a MethodChannel to bridge this in Swift, but would prefer not to write or maintain native Swift code if possible.
I've looked for a prebuilt Flutter package to handle this, but nothing exists or is up-to-date on pub.dev.
Main Question:
Is there any Apple-supported way to generate the device_token for DeviceCheck from a Flutter app without writing Swift code manually?
If not, is DCDevice.generateToken() the only possible approach, and must I implement this via Swift and Flutter platform channels?
Thanks!
Hello,
I'm currently investigating an issue related to iOS credit card autofill (Payments & Card Details) in our mobile application.
Our app is built using React Native, and we are implementing card input fields using TextInput with the required autofill configuration:
autoComplete="cc-number"
textContentType="creditCardNumber"
Despite correctly configuring these properties, credit card autofill is not being triggered on iOS devices.
I would appreciate clarification on:
Is credit card autofill officially supported for React Native TextInput fields using autoComplete="cc-number" and textContentType="creditCardNumber"?
Are there any additional requirements (entitlements, associated domains, specific configurations, etc.) needed for payment autofill to work?
Is autofill expected to work inside WKWebView contexts?
Are there any known limitations or restrictions for third-party frameworks such as React Native?
I would appreciate any guidance or documentation you can share regarding the expected behavior and official support for this scenario
Hello Apple community !
Not here to report an issue but I just wanted to make a suggestion ^^
I feel like a common frustration amongst developers is the lack of transparency over bugs filed on developer tools, SDKs, iOS versions, the whole Apple ecosystem really.
This leads to the creation of parallel bug tracking tools (https://github.com/feedback-assistant/reports?tab=readme-ov-file /
https://openradar.appspot.com/page/1) or filing of duplicates for reports that may already exist and are being worked on.
I feel like this would save time for both external developers that encounter bugs & Apple engineers that have to look for possible duplicates to share a common public database of issues.
Other companies have this kind of system in place (Google for example : https://issuetracker.google.com/) so why not Apple ?
Thank you
I'm attempting to create a proof of concept of a static library, distributed as an XCFramework, which has two local XCFramework dependencies.
The reason for this is because I'm working to provide a single statically linked library to a customer, instead of providing them with the static library plus the two dependencies.
The Issue
With a fairly simple example project, I'm not able to access any code from the static library without the complier throwing a "No such module" error and saying that it cannot find one of the dependent modules.
Project Layout
I have an example project that has some example targets with basic example code.
Example Project on Github
Target: FrameworkA
Mach-0 Type: Dynamic
Build Mergable Library: Yes
Skip Install: No
Build Libraries For Distribution: Yes
Target: FrameworkB
Mach-0 Type: Dynamic
Build Mergable Library: Yes
Skip Install: No
Build Libraries For Distribution: Yes
XCFrameworks are being generated from these two targets using Apple's recommendations. I've verified that the mergable metadata is present in both framework's Info.plist files.
Each exposes a single struct which will return an example String.
Finally I have my SDK target:
Target: ExampleKit
Mach-0 Type: Static
Build Mergable Library: No
Create Merged Binary: Manual
Skip Install: No
Build Libraries For Distribution: Yes
The two .xcframework files are in the Target's folder structure as well. The "Link Binary With Libraries" build phase includes them and they're Required.
Inside of the ExampleKit target, I have a single public struct which has two static properties which return the example strings from FrameworkA and FrameworkB.
I then have another script which generates an XCFramework from this target.
Expectations
Based on Apple's documentation and the "Meet Mergable Libraries" WWDC session I would expect that I could make a simple iOS app, link the ExampleKit.xcframework, import ExampleKit inside of a file, and be able to access the single public struct present in ExampleKit. Unfortunately, all I get is "No such module FrameworkA".
I would expect that FrameworkA and FrameworkB would have been merged into ExampleKit? I'm really unsure of where to go from here in debugging this. And more importantly, is this even a possible thing to do?
I am developing an iOS in-app SDK for collecting code coverage data. The SDK writes coverage data to a specified file by calling __llvm_profile_set_filename and __llvm_profile_write_file. This implementation worked correctly until I switched to Xcode 26.0 to build my project. Now, when __llvm_profile_write_file() is executed, it crashes with the following error stack. Can anyone provide any assistance?
Exception Type: EXC_BAD_ACCESS (SIGSEGV)
Exception Subtype: KERN_INVALID_ADDRESS at 0x0000000000000001
Exception Codes: 0x0000000000000001, 0x0000000000000001
Termination Reason: Namespace SIGNAL, Code 11, Segmentation fault: 11
Terminating Process: exc handler [454]
Thread 96 name: Dispatch queue: com.test-coverage.processing
Thread 96: Crashed:
0 Demo 0x122602ea8 initializeValueProfRuntimeRecord (in Demo) (InstrProfilingValue.c:351)
1 Demo 0x00000001226064c0 writeOneValueProfData (in Demo) (InstrProfilingWriter.c:153)
2 Demo 0x0000000122606308 writeValueProfData (in Demo) (InstrProfilingWriter.c:234)
3 Demo 0x00000001226060d0 lprofWriteDataImpl (in Demo) (InstrProfilingWriter.c:401)
4 Demo 0x0000000122605d98 lprofWriteData (in Demo) (InstrProfilingWriter.c:261)
5 Demo 0x0000000122604804 writeFile (in Demo) (InstrProfilingFile.c:536)
6 Demo 0x122604664 __llvm_profile_write_file_alias + 228
7 Demo 0x000000011c6dd108 -[BDTestCoverage p_dumpMainCoverageInfoWithCustomKey:] (in Demo) (TestCoverage.m:995)
8 Demo 0x000000011c6dcef8 -[BDTestCoverage p_dumpAllCoverageProfileWithCustomKey:] (in Demo) (TestCoverage.m:970)
In Simulator Korean character system has not working well.
I want to type "", however, if I type the same thing on the simulator's virtual keyboard (Korean), it comes out as ''.
I think this is caused by IME system in ios simulator bug. I think this has been happening since IOS 17.
I need to install the AirPlay profile on an iphone to watch decrypted traffic in ATS for development work on CarPlay.
The documentation for ATS says to click "Utilities -> Download Profiles -> AirPlay Diagnostic Mode".
When I do this, it brings up a file dialog, presumably to select a location to download. But nothing happens. The other profiles launch a web browser and download the .mobileconfig profile.
How do I get the AirPlay profile? Am I misunderstanding how this is supposed to work?
I found ATSAssetsInfoDefault.plist which references these files. And they all have https://developer.apple.com/services-account/download?path=/iOS/iOS_Logs/... except the AirPlay profile, which is type "slug" and just says ats-airplay-diagnostic-mode-profile.
Is this a bug in the app?
Apple’s library technology has a long and glorious history, dating all the way back to the origins of Unix. This does, however, mean that it can be a bit confusing to newcomers. This is my attempt to clarify some terminology.
If you have any questions or comments about this, start a new thread and tag it with Linker so that I see it.
Share and Enjoy
—
Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"
An Apple Library Primer
Apple’s tools support two related concepts:
Platform — This is the platform itself; macOS, iOS, iOS Simulator, and Mac Catalyst are all platforms.
Architecture — This is a specific CPU architecture used by a platform. arm64 and x86_64 are both architectures.
A given architecture might be used by multiple platforms. The most obvious example of this arm64, which is used by all of the platforms listed above.
Code built for one platform will not work on another platform, even if both platforms use the same architecture.
Code is usually packaged in either a Mach-O file or a static library. Mach-O is used for executables (MH_EXECUTE), dynamic libraries (MH_DYLIB), bundles (MH_BUNDLE), and object files (MH_OBJECT). These can have a variety of different extensions; the only constant is that .o is always used for a Mach-O containing an object file. Use otool and nm to examine a Mach-O file. Use vtool to quickly determine the platform for which it was built. Use size to get a summary of its size. Use dyld_info to get more details about a dynamic library.
IMPORTANT All the tools mentioned here are documented in man pages. For information on how to access that documentation, see Reading UNIX Manual Pages. There’s also a Mach-O man page, with basic information about the file format.
Many of these tools have old and new variants, using the -classic suffix or llvm- prefix, respectively. For example, there’s nm-classic and llvm-nm. If you run the original name for the tool, you’ll get either the old or new variant depending on the version of the currently selected tools. To explicitly request the old or new variants, use xcrun.
The term Mach-O image refers to a Mach-O that can be loaded and executed without further processing. That includes executables, dynamic libraries, and bundles, but not object files.
A dynamic library has the extension .dylib. You may also see this called a shared library.
A framework is a bundle structure with the .framework extension that has both compile-time and run-time roles:
At compile time, the framework combines the library’s headers and its stub library (stub libraries are explained below).
At run time, the framework combines the library’s code, as a Mach-O dynamic library, and its associated resources.
The exact structure of a framework varies by platform. For the details, see Placing Content in a Bundle.
macOS supports both frameworks and standalone dynamic libraries. Other Apple platforms support frameworks but not standalone dynamic libraries.
Historically these two roles were combined, that is, the framework included the headers, the dynamic library, and its resources. These days Apple ships different frameworks for each role. That is, the macOS SDK includes the compile-time framework and macOS itself includes the run-time one. Most third-party frameworks continue to combine these roles.
A static library is an archive of one or more object files. It has the extension .a. Use ar, libtool, and ranlib to inspect and manipulate these archives.
The static linker, or just the linker, runs at build time. It combines various inputs into a single output. Typically these inputs are object files, static libraries, dynamic libraries, and various configuration items. The output is most commonly a Mach-O image, although it’s also possible to output an object file. The linker may also output metadata, such as a link map (see Using a Link Map to Track Down a Symbol’s Origin).
The linker has seen three major implementations:
ld — This dates from the dawn of Mac OS X.
ld64 — This was a rewrite started in the 2005 timeframe. Eventually it replaced ld completely. If you type ld, you get ld64.
ld_prime — This was introduced with Xcode 15. This isn’t a separate tool. Rather, ld now supports the -ld_classic and -ld_new options to select a specific implementation.
Note During the Xcode 15 beta cycle these options were -ld64 and -ld_prime. I continue to use those names because the definition of new changes over time (some of us still think of ld64 as the new linker ;–).
The dynamic linker loads Mach-O images at runtime. Its path is /usr/lib/dyld, so it’s often referred to as dyld, dyld, or DYLD. Personally I pronounced that dee-lid, but some folks say di-lid and others say dee-why-el-dee.
IMPORTANT Third-party executables must use the standard dynamic linker.
Other Unix-y platforms support the notion of a statically linked executable, one that makes system calls directly. This is not supported on Apple platforms. Apple platforms provide binary compatibility via system dynamic libraries and frameworks, not at the system call level.
Note Apple platforms have vestigial support for custom dynamic linkers (your executable tells the system which dynamic linker to use via the LC_LOAD_DYLINKER load command). This facility originated on macOS’s ancestor platform and has never been a supported option on any Apple platform.
The dynamic linker has seen 4 major revisions. See WWDC 2017 Session 413 (referenced below) for a discussion of versions 1 through 3. Version 4 is basically a merging of versions 2 and 3.
The dyld man page is chock-full of useful info, including a discussion of how it finds images at runtime.
Every dynamic library has an install name, which is how the dynamic linker identifies the library. Historically that was the path where you installed the library. That’s still true for most system libraries, but nowadays a third-party library should use an rpath-relative install name. For more about this, see Dynamic Library Identification.
Mach-O images are position independent, that is, they can be loaded at any location within the process’s address space. Historically, Mach-O supported the concept of position-dependent images, ones that could only be loaded at a specific address. While it may still be possible to create such an image, it’s no longer a good life choice.
Mach-O images have a default load address, also known as the base address. For modern position-independent images this is 0 for library images and 4 GiB for executables (leaving the bottom 32 bits of the process’s address space unmapped). When the dynamic linker loads an image, it chooses an address for the image and then rebases the image to that address. If you take that address and subtract the image’s load address, you get a value known as the slide.
Xcode 15 introduced the concept of a mergeable library. This a dynamic library with extra metadata that allows the linker to embed it into the output Mach-O image, much like a static library. Mergeable libraries have many benefits. For all the backstory, see WWDC 2023 Session 10268 Meet mergeable libraries. For instructions on how to set this up, see Configuring your project to use mergeable libraries.
If you put a mergeable library into a framework structure you get a mergeable framework.
Xcode 15 also introduced the concept of a static framework. This is a framework structure where the framework’s dynamic library is replaced by a static library.
Note It’s not clear to me whether this offers any benefit over creating a mergeable framework.
Earlier versions of Xcode did not have proper static framework support. That didn’t stop folks trying to use them, which caused all sorts of weird build problems.
A universal binary is a file that contains multiple architectures for the same platform. Universal binaries always use the universal binary format. Use the file command to learn what architectures are within a universal binary. Use the lipo command to manipulate universal binaries.
A universal binary’s architectures are either all in Mach-O format or all in the static library archive format. The latter is called a universal static library.
A universal binary has the same extension as its non-universal equivalent. That means a .a file might be a static library or a universal static library.
Most tools work on a single architecture within a universal binary. They default to the architecture of the current machine. To override this, pass the architecture in using a command-line option, typically -arch or --arch.
An XCFramework is a single document package that includes libraries for any combination of platforms and architectures. It has the extension .xcframework. An XCFramework holds either a framework, a dynamic library, or a static library. All the elements must be the same type. Use xcodebuild to create an XCFramework. For specific instructions, see Xcode Help > Distribute binary frameworks > Create an XCFramework.
Historically there was no need to code sign libraries in SDKs. If you shipped an SDK to another developer, they were responsible for re-signing all the code as part of their distribution process. Xcode 15 changes this. You should sign your SDK so that a developer using it can verify this dependency. For more details, see WWDC 2023 Session 10061 Verify app dependencies with digital signatures and Verifying the origin of your XCFrameworks.
A stub library is a compact description of the contents of a dynamic library. It has the extension .tbd, which stands for text-based description (TBD). Apple’s SDKs include stub libraries to minimise their size; for the backstory, read this post. Use the tapi tool to create and manipulate stub libraries. In this context TAPI stands for a text-based API, an alternative name for TBD. Oh, and on the subject of tapi, I’d be remiss if I didn’t mention tapi-analyze!
Stub libraries currently use YAML format, a fact that’s relevant when you try to interpret linker errors. If you’re curious about the format, read the tapi-tbdv4 man page. There’s also a JSON variant documented in the tapi-tbdv5 man page.
Note Back in the day stub libraries used to be Mach-O files with all the code removed (MH_DYLIB_STUB). This format has long been deprecated in favour of TBD.
Historically, the system maintained a dynamic linker shared cache, built at runtime from its working set of dynamic libraries. In macOS 11 and later this cache is included in the OS itself. Libraries in the cache are no longer present in their original locations on disk:
% ls -lh /usr/lib/libSystem.B.dylib
ls: /usr/lib/libSystem.B.dylib: No such file or directory
Apple APIs, most notably dlopen, understand this and do the right thing if you supply the path of a library that moved into the cache. That’s true for some, but not all, command-line tools, for example:
% dyld_info -exports /usr/lib/libSystem.B.dylib
/usr/lib/libSystem.B.dylib [arm64e]:
-exports:
offset symbol
…
0x5B827FE8 _mach_init_routine
% nm /usr/lib/libSystem.B.dylib
…/nm: error: /usr/lib/libSystem.B.dylib: No such file or directory
When the linker creates a Mach-O image, it adds a bunch of helpful information to that image, including:
The target platform
The deployment target, that is, the minimum supported version of that platform
Information about the tools used to build the image, most notably, the SDK version
A build UUID
For more information about the build UUID, see TN3178 Checking for and resolving build UUID problems. To dump the other information, run vtool.
In some cases the OS uses the SDK version of the main executable to determine whether to enable new behaviour or retain old behaviour for compatibility purposes. You might see this referred to as compiled against SDK X. I typically refer to this as a linked-on-or-later check.
Apple tools support the concept of autolinking. When your code uses a symbol from a module, the compiler inserts a reference (using the LC_LINKER_OPTION load command) to that module into the resulting object file (.o). When you link with that object file, the linker adds the referenced module to the list of modules that it searches when resolving symbols.
Autolinking is obviously helpful but it can also cause problems, especially with cross-platform code. For information on how to enable and disable it, see the Build settings reference.
Mach-O uses a two-level namespace. When a Mach-O image imports a symbol, it references the symbol name and the library where it expects to find that symbol. This improves both performance and reliability but it precludes certain techniques that might work on other platforms. For example, you can’t define a function called printf and expect it to ‘see’ calls from other dynamic libraries because those libraries import the version of printf from libSystem.
To help folks who rely on techniques like this, macOS supports a flat namespace compatibility mode. This has numerous sharp edges — for an example, see the posts on this thread — and it’s best to avoid it where you can. If you’re enabling the flat namespace as part of a developer tool, search the ’net for dyld interpose to learn about an alternative technique.
WARNING Dynamic linker interposing is not documented as API. While it’s a useful technique for developer tools, do not use it in products you ship to end users.
Apple platforms use DWARF. When you compile a file, the compiler puts the debug info into the resulting object file. When you link a set of object files into a executable, dynamic library, or bundle for distribution, the linker does not include this debug info. Rather, debug info is stored in a separate debug symbols document package. This has the extension .dSYM and is created using dsymutil. Use symbols to learn about the symbols in a file. Use dwarfdump to get detailed information about DWARF debug info. Use atos to map an address to its corresponding symbol name.
Different languages use different name mangling schemes:
C, and all later languages, add a leading underscore (_) to distinguish their symbols from assembly language symbols.
C++ uses a complex name mangling scheme. Use the c++filt tool to undo this mangling.
Likewise, for Swift. Use swift demangle to undo this mangling.
For a bunch more info about symbols in Mach-O, see Understanding Mach-O Symbols. This includes a discussion of weak references and weak definition. If your code is referencing a symbol unexpectedly, see Determining Why a Symbol is Referenced.
To remove symbols from a Mach-O file, run strip. To hide symbols, run nmedit.
It’s common for linkers to divide an object file into sections. You might find data in the data section and code in the text section (text is an old Unix term for code). Mach-O uses segments and sections. For example, there is a text segment (__TEXT) and within that various sections for code (__TEXT > __text), constant C strings (__TEXT > __cstring), and so on.
Over the years there have been some really good talks about linking and libraries at WWDC, including:
WWDC 2023 Session 10268 Meet mergeable libraries
WWDC 2022 Session 110362 Link fast: Improve build and launch times
WWDC 2022 Session 110370 Debug Swift debugging with LLDB
WWDC 2021 Session 10211 Symbolication: Beyond the basics
WWDC 2019 Session 416 Binary Frameworks in Swift — Despite the name, this covers XCFrameworks in depth.
WWDC 2018 Session 415 Behind the Scenes of the Xcode Build Process
WWDC 2017 Session 413 App Startup Time: Past, Present, and Future
WWDC 2016 Session 406 Optimizing App Startup Time
Note The older talks are no longer available from Apple, but you may be able to find transcripts out there on the ’net.
Historically Apple published a document, Mac OS X ABI Mach-O File Format Reference, or some variant thereof, that acted as the definitive reference to the Mach-O file format. This document is no longer available from Apple. If you’re doing serious work with Mach-O, I recommend that you find an old copy. It’s definitely out of date, but there’s no better place to get a high-level introduction to the concepts. The Mach-O Wikipedia page has a link to an archived version of the document.
For the most up-to-date information about Mach-O, see the declarations and doc comments in <mach-o/loader.h>.
Revision History
2025-08-04 Added a link to Determining Why a Symbol is Referenced.
2025-06-29 Added information about autolinking.
2025-05-21 Added a note about the legacy Mach-O stub library format (MH_DYLIB_STUB).
2025-04-30 Added a specific reference to the man pages for the TBD format.
2025-03-01 Added a link to Understanding Mach-O Symbols. Added a link to TN3178 Checking for and resolving build UUID problems. Added a summary of the information available via vtool. Discussed linked-on-or-later checks. Explained how Mach-O uses segments and sections. Explained the old (-classic) and new (llvm-) tool variants. Referenced the Mach-O man page. Added basic info about the strip and nmedit tools.
2025-02-17 Expanded the discussion of dynamic library identification.
2024-10-07 Added some basic information about the dynamic linker shared cache.
2024-07-26 Clarified the description of the expected load address for Mach-O images.
2024-07-23 Added a discussion of position-independent images and the image slide.
2024-05-08 Added links to the demangling tools.
2024-04-30 Clarified the requirement to use the standard dynamic linker.
2024-03-02 Updated the discussion of static frameworks to account for Xcode 15 changes. Removed the link to WWDC 2018 Session 415 because it no longer works )-:
2024-03-01 Added the WWDC 2023 session to the list of sessions to make it easier to find. Added a reference to Using a Link Map to Track Down a Symbol’s Origin. Made other minor editorial changes.
2023-09-20 Added a link to Dynamic Library Identification. Updated the names for the static linker implementations (-ld_prime is no more!). Removed the beta epithet from Xcode 15.
2023-06-13 Defined the term Mach-O image. Added sections for both the static and dynamic linkers. Described the two big new features in Xcode 15: mergeable libraries and dependency verification.
2023-06-01 Add a reference to tapi-analyze.
2023-05-29 Added a discussion of the two-level namespace.
2023-04-27 Added a mention of the size tool.
2023-01-23 Explained the compile-time and run-time roles of a framework. Made other minor editorial changes.
2022-11-17 Added an explanation of TAPI.
2022-10-12 Added links to Mach-O documentation.
2022-09-29 Added info about .dSYM files. Added a few more links to WWDC sessions.
2022-09-21 First posted.
We're having issues getting Sign in with Google to function on TestFlight (not experiencing these issues on iOS Browser) with user unable to be authorised and proceed to logged in screens of our app.
Below are the three sign-in methods tested and the exact results for each.
Button 1: Default
Standard Google Sign-In button (Google JavaScript SDK) embedded in the frontend.
Uses the normal OAuth browser redirect flow.
Auth URL: https://accounts.google.com/o/oauth2/v2/auth?...
Sometimes disallowed_useragent error.
Other times a 400 invalid_request error.
In most cases the callback is never triggered inside the wrapper.
Appears that the wrapper does not retain cookies/session data from the external Google window.
Button 2: Custom
Custom button calling Google OAuth through our own redirect handler.
Explicitly set a custom user-agent to bypass disallowed user agent logic.
Later removed user-agent override entirely for testing.
Added multiple ATS (App Transport Security) exceptions for Google domains.
Added custom URL scheme to Info.plist for OAuth redirect.
Changing the user-agent had no effect.
ATS exceptions + scheme support verified and working.
Redirect still fails to propagate tokens back to the WebView.
In tests a few weeks ago we got to Google’s login page, but it never returned to the app with a valid code. Now
we are consistently getting disallowed_useragent error.
Button 3: Default
Same as Button 1 however tested outside of Vue.js with just plain JavaScript.
Added new Google domain exceptions and updated redirect URIs.
Behaviour matches Button 1
Google account selection sometimes worked, however now consitently disallowed_useragent error
Additional Technical Attempts
User-Agent Modifications
Set UA to standard desktop Chrome → no effect.
Removed UA override → no effect.
ATS / Domain / Scheme Configuration
Added:
accounts.google.com
.googleusercontent.com
*.googleapis.com
I have an issue when i use external tester with a public link and emails.
Test fly is well installed but when i have to open the app, it just charge as seen in the screen.
I have a project inside the project structure. I have around 300 unit tests in the project.
I see that for some of the subprojects, the coverage numbers show up correctly, but for other subprojects and the main project, the coverage number shows zero, even though the tests are running successfully.
The log I get is:
Aggregation tool emitted warnings:
warning: /Users/ABC/Library/Developer/Xcode/DerivedData/projectABC-hfzmkbdgpiswoxfvvnvhrafaiqyb/Build/ProfileData/A8EEC1FB-1699-4C29-A88C-D3DDA226DBC0/0A416494-A393-4319-AA47-502D72084C9C-43351.profraw: raw profile version mismatch: Profile uses raw profile format version = 8; expected version = 10
PLEASE update this tool to the version in the raw profile, or regenerate the raw profile with the expected version.
I only have one Xcode (26.0.1) on my machine. I tried cleaning the derived data, the cleaning project, and rerunning the tests, but it hasn't helped.
Please help me get the coverage number back. Thank you.
I'm trying to authenticate to a git host using SSH keys stored in 1Password. I have ~/.ssh/config with mode 600 set with a symlink:
Host *
IdentityAgent "~/.1password/agent.sock"
But ssh-add -l shows no identities. If I set $SSH_AUTH_SOCK, ssh-add -l works just fine. I'd love to not have to do this, though.
Why doesn't ssh-add seem to read ~/.ssh/config? The built-in version is OpenSSH_10.0p2, LibreSSL 3.3.6.
I've searched fruitlessly for an answer anywhere else.
I'm a newbie to on-demand resources and I feel like I'm missing something very obvious. I've successfully tagged and set up ODR in my Xcode project, but now I want to upload the assets to my own server so I can retrieve them from within the app, and I can't figure out how to export the files I need.
I'm following the ODR Guide and I'm stuck at Step #4, after I've selected my archive in the Archives window it says to "Click the Export button", but this is what I see:
As shown in the screenshot, there is no export button visible. I have tried different approaches, including distributing to appstore connect, and doing a local development release. The best I've been able to do is find a .assetpack folder inside the archive package through the finder, but uploading that, or the asset.car inside it, just gives me a "cannot parse response" error from the ODR loading code. I've verified I uploaded those to the correct URL.
Can anyone walk me through how to save out the file(s) I need, in a form I can just upload to my server?
Thanks,
Pete
So I'm testing a microapp that is contained in an IPFS folder. I use a web3 website that is used to view NFTs and their IPFS files. The app has gyro controls, which are enabled through a confirmation gesture.
In iOS 18.5, when I press "Request Permission" button I get the popup to allow the app to acess movement and orientation. In iOS26, pressing the button does nothing. Keep in mind that this only happens through the website, that uses iframes. When I load the IPFS file from a direct link, the popup appears with no issue.
I think this might be because iOS26 uses WebGPU or it might be a bug since iOS26 is still in beta.
I am developing an Augmented Reality (AR) navigation application for the iPad, utilizing the ARCL library to place Points of Interest (POIs) in the real world.
The application's behavior varies significantly based on the device's networking configuration:
Cellular Network (Expected Behavior): On an iPad with a cellular modem, when using the cellular network, all POIs are placed accurately with correct orientation.
Wi-Fi Only (Expected Behavior): On a Wi-Fi-only model (no GPS chip), POI placement is inaccurate, confirming the need for an external GPS receiver for that hardware configuration.
Cellular + Wi-Fi (Anomalous Behavior):
The iPad is a cellular model (equipped with GNSS/GPS).
The device is connected to a Wi-Fi network (enforced via an MDM profile, preventing the user from disabling Wi-Fi).
When actively connected to this specific Wi-Fi network, the AR POIs consistently display with an incorrect orientation and placement, even though the device hardware has a dedicated GPS chip. The placement error strongly suggests that the device's determined location or heading is erroneous. It appears that the active Wi-Fi connection is somehow interfering with or overriding the high-accuracy GNSS/GPS data, leading to a flawed Core Location determination that negatively impacts the ARCL world tracking and anchor placement.
Has anyone experienced a scenario where an active Wi-Fi connection on a cellular iPad model causes Core Location to prioritize less accurate location data (potentially Wi-Fi-based location services) over the device's built-in GNSS/GPS, resulting in severe orientation errors? We observed that on Apple map(native application) as well it is showing wrong location and orientation when it is connected to WiFi