Are there some undocumented (or, well, documented, but overlooked by me) prerequisites to the readValueWithCompletionHandler: method?
The reason I ask is that occasionally I am getting the Read/Write operation failed error in the callback, even in cases where direct, non-deferred reading of the value worked properly. It seems to happen very consistently with some accessories and characteristics, not randomly; thus, it is not likely a temporary quirk in the communication with the device.
Probably I am overlooking something of importance, but it does not make a good sense to me. My code (is it right, or can you see anything wrong in there?)
// in an HMCharacteristic category
if ([self.properties containsObject:HMCharacteristicPropertyReadable]) {
id val=self.value, ident=[NSString stringWithFormat:@" [%@] %@ (%@)", self.uniqueIdentifier, self.localizedDescription, self.service.accessory.name];
NSLog(@"nondeferred '%@'%@", val, ident);
if (self.service.accessory.reachable) {
[self readValueWithCompletionHandler:^(NSError * _Nullable error) {
if (error) NSLog(@"deferred ERROR %@ -> %@", ident, error);
else NSLog(@"deferred '%@'%@", self.value, ident);
}];
}
}
for most accessories/characteristics works properly, but for some of them I am consistently getting results like
nondeferred '70.5' [64998F70-9C11-502F-B8B4-E99DC5C3171B] Current Relative Humidity (Vlhkoměr TH)
deferred '70.5' ERROR [64998F70-9C11-502F-B8B4-E99DC5C3171B] Current Relative Humidity (Vlhkoměr TH) -> Error Domain=HMErrorDomain Code=74 "Read/Write operation failed." UserInfo={NSLocalizedDescription=Read/Write operation failed.}
Do I do something wrong in my code, or is that normal with some devices?
If the latter, is there perhaps a way to know beforehand that I should not use readValueWithCompletionHandler: (for it is bound to fail anyway), and instead I should simply use self.value non-deferred? For some time it seemed to me it happens with bridged accessories, but not really, this hypothesis proved wrong by further testing.
Thanks!
