title: averagePowerForChannel working with iOSimulator but don't on iPad
body: <p>In my small application for iOS 8.0 I'm measuring microphone's input level and if it's greater than -40 dB I'm changing the image in UIImageView and playing mp3-file. It works great in iOSimulator but doesn't work on iPad iOS 8.0. (microphone is accessible for app). What's the issue?
  Thanks.</p>
  
  <pre><code>//  ViewController.m
  
  #import "ViewController.h"
  #import "AVFoundation/AVAudioPlayer.h"
  #import &lt;AVFoundation/AVFoundation.h&gt;
  
  @interface ViewController ()
  @end
  
  @implementation ViewController
  
  NSTimer *meterTimer;
  AVAudioRecorder *recorder;
  AVAudioPlayer *player;
  NSString *audioFilePath; NSURL *pathAsURL;   // for audioplayer
  
  - (void)viewDidLoad
   {   [super viewDidLoad];
  
  meterTimer = [NSTimer scheduledTimerWithTimeInterval:0.3    // sets timer interrupt
  target:self selector:@selector(timerArrived) userInfo:nil repeats:YES];
  
  NSDictionary *settings = [NSDictionary dictionaryWithObjectsAndKeys:
                            [NSNumber numberWithFloat: 44100.0],AVSampleRateKey,
                            [NSNumber numberWithInt: kAudioFormatAppleLossless],AVFormatIDKey,
                            [NSNumber numberWithInt: 1],AVNumberOfChannelsKey,
                            [NSNumber numberWithInt: AVAudioQualityMax],AVEncoderAudioQualityKey,nil];
  NSError *error;
  recorder = [[AVAudioRecorder alloc] initWithURL:[NSURL URLWithString:[NSTemporaryDirectory()
              stringByAppendingPathComponent:@"tmp.caf"]]  settings:settings error:&amp;error];
  [recorder prepareToRecord];
  recorder.meteringEnabled = YES;
  [recorder record];
  }
  
  - (void)timerArrived    // called by timer
  {   int intPower; float fValue;
      [recorder updateMeters];    // check input level
      fValue = [recorder averagePowerForChannel:0];
      intPower = roundf(fValue);
      if (intPower &gt; -40)
  {   _microphImage.image = [UIImage imageNamed:@"Microphone2.png"];
      audioFilePath = [[NSBundle mainBundle] pathForResource:@"aga" ofType:@"mp3"];
      pathAsURL = [[NSURL alloc] initFileURLWithPath:audioFilePath]; NSError *error;
      player = [[AVAudioPlayer alloc] initWithContentsOfURL:pathAsURL error:&amp;error];
      [player play];
  }
  else {_microphImage.image = [UIImage imageNamed:@"Microphone.png"];}
  }
  
  - (void)didReceiveMemoryWarning {[super didReceiveMemoryWarning];} 
  @end
  </code></pre>