AVAudioRecorder stopped working on iPad - ios

Question

I have an app that was published for IOS9: a relatively minor feature is the ability to record small sound segments. While testing a similar feature on a new app, I found that the same code did not work on an iPad running iOS10, although it works on the simulator. On the iPad, audio metering gives a steady -120dB, and audioRecorderDidFinishRecording is never called. There are no logged messages. Both the published app and the new app do not work on the iPad.
The code looks like this:
- (void) record: (int) record_time {
record_sound = self;
AVAudioSession *audioSession = [AVAudioSession sharedInstance];
NSError *err = nil;
[audioSession setCategory :AVAudioSessionCategoryPlayAndRecord error:&err];
if(err){
NSLog(#"audioSession: %# %ld %#", [err domain], (long)[err code], [[err userInfo] description]);
return;
}
[audioSession setActive:YES error:&err];
err = nil;
if(err){
NSLog(#"audioSession: %# %ld %#", [err domain], (long)[err code], [[err userInfo] description]);
return;
}
NSMutableDictionary * recordSetting = [[NSMutableDictionary alloc] init];
[recordSetting setValue :[NSNumber numberWithInt:kAudioFormatLinearPCM] forKey:AVFormatIDKey];
[recordSetting setValue:[NSNumber numberWithFloat:44100.0] forKey:AVSampleRateKey];
[recordSetting setValue:[NSNumber numberWithInt: 1] forKey:AVNumberOfChannelsKey];
[recordSetting setValue :[NSNumber numberWithInt:16] forKey:AVLinearPCMBitDepthKey];
[recordSetting setValue :[NSNumber numberWithBool:NO] forKey:AVLinearPCMIsBigEndianKey];
[recordSetting setValue :[NSNumber numberWithBool:NO] forKey:AVLinearPCMIsFloatKey];
// Create a new file
NSString * recorderFilePath = [Recorder getRecordFilename];
NSFileManager * fileManager = [NSFileManager defaultManager];
NSError * error = nil;
[fileManager createDirectoryAtPath:[recorderFilePath stringByDeletingLastPathComponent] withIntermediateDirectories:YES attributes:nil error:&error]; //Create folder
NSURL *url = [NSURL fileURLWithPath:recorderFilePath];
err = nil;
recorder = [[ AVAudioRecorder alloc] initWithURL:url settings:recordSetting error:&err];
if(!recorder){
NSLog(#"recorder: %# %ld %#", [err domain], (long)[err code], [[err userInfo] description]);
return;
}
//prepare to record
[recorder setDelegate:self];
[recorder prepareToRecord];
recorder.meteringEnabled = YES;
// start recording
[recorder recordForDuration:(NSTimeInterval) record_time];
recordEndTime = [[NSDate date] dateByAddingTimeInterval: (NSTimeInterval) (record_time + 0.5)];
}

Answer 1

I switched off the iPad and restarted it, and everything started working again. Something must have got locked up inside the AVAudioRecorder mechanism.