recordForDuration hangs up, doesn't stop recording

Question

when i set up an audio recorder and just use a button to start/stop the "record" function call, everything seems to work fine. however, when i use a separate button to start the "recordForDuration" function call. it seems to just keep on recording or perhaps it thinks its recording. either way, it does not stop after the requested time duration. the while loop below the call just keeps spitting out "recording..." to the debug window forever. any ideas? this code was basically plucked from some working code i had in xcode5 that runs fine on iphone 5s with ios7.1. the code hangs up with anything running ios8.1 (also hangs up in 8.1 simulator). see my code below. thanks for any advice.

- (void)viewDidLoad {
[super viewDidLoad];
recordSwitchOn=NO;

//setup generic audio session
audioSession = [AVAudioSession sharedInstance];
[audioSession setCategory :AVAudioSessionCategoryPlayAndRecord error:nil];
[audioSession setActive:YES error:nil];

NSLog(@"setupRecorder:");
inFileName = [NSString stringWithFormat:@"recordedData.caf"];//5
inFilePath = [NSTemporaryDirectory() stringByAppendingPathComponent:inFileName];
inFileURL = [NSURL fileURLWithPath:inFilePath];

recordSetting = [[NSMutableDictionary alloc] init];

[recordSetting setValue :[NSNumber numberWithInt:kAudioFormatLinearPCM] forKey:AVFormatIDKey];
[recordSetting setValue:[NSNumber numberWithFloat:40000] forKey:AVSampleRateKey];
[recordSetting setValue:[NSNumber numberWithInt: 1] forKey:AVNumberOfChannelsKey];
[recordSetting setValue:[NSNumber numberWithInt:AVAudioQualityMax] forKey:AVEncoderAudioQualityKey];


//    get audio file and put into a file ID
//    AudioFileID fileID; //in header

AudioFileOpenURL((__bridge CFURLRef)inFileURL, kAudioFileReadWritePermission, kAudioFileCAFType,&inputFileID);

//    initialize my audio recorders
inputRecorder = [[AVAudioRecorder alloc] initWithURL:inFileURL settings:recordSetting error:nil];
if (inputRecorder) {NSLog(@"inputRecorder is setup");
}else{NSLog(@"error setting up inputRecorder");}


}

- (IBAction)rec4durButt:(id)sender {
[statusLabel setText:@"Recording..."];
[inputRecorder setDelegate:self];
[inputRecorder recordForDuration:2.0];
while([inputRecorder isRecording]){
    NSLog(@"recording...");
}
[statusLabel setText:@"Recording stopped"];
}


- (IBAction)recButt:(id)sender {
if(recordSwitchOn==NO){
    [statusLabel setText:@"Recording..."];
    recordSwitchOn=YES;
    [inputRecorder setDelegate:self];
    //    [inputRecorder recordForDuration:(NSTimeInterval)0.35];
    [inputRecorder record];
}else{
    [statusLabel setText:@"Recording stopped"];
    recordSwitchOn=NO;
    [inputRecorder stop];
}
}

Answer 1

It seems that looping on the main thread blocks some aspect of the AVAudioRecorder from updating its recording status (or even getting started). By removing the loop, you free the recorder up to do its normal processing.

The delegate provides a method (audioRecorderDidFinishRecording:successfully:) that signals the completion of recording, so drop the while loop and implement that.

Answer 2

If you want continuous recording, recording exception may occur, so you should be one second after recording, I think, may be caused by audio cache