title: iOs ExtAudioFileCreateWithURL - Getting error Creating file ('fmt?')
body: <p>Hi I've been trying to create a wav audio file from the below code, but keep getting the error Creating file ('fmt?'). Can anyone help me out here ? Thanks. </p>
  
  <p>My log : 
  *2012-11-01 13:33:14.183 Novocaine iOS Example[7456:c07] URL: file://localhost/Users/pier/Library/Application%20Support/iPhone%20Simulator/6.0/Applications/01EBF2C0-2C3A-490D-835E-9C39A3E88E0B/Documents/testrecording.wav</p>
  
  <p>Error: Creating file ('fmt?')*</p>
  
  <pre><code>- (id)initWithAudioFileURL:(NSURL *)urlToAudioFile samplingRate:(float)thisSamplingRate numChannels:(UInt32)thisNumChannels
  {
  self = [super init];
  if (self)
  {
  
      // Zero-out our timer, so we know we're not using our callback yet
      self.callbackTimer = nil;
  
  
      // Open a reference to the audio file
      self.audioFileURL = urlToAudioFile;
      CFURLRef audioFileRef = (CFURLRef)self.audioFileURL;
  
      AudioStreamBasicDescription outputFileDesc; 
  
      // Set a few defaults and presets
      self.samplingRate = thisSamplingRate;
      self.numChannels = thisNumChannels;
      self.currentTime = 0.0;
      self.latency = .011609977; // 512 samples / ( 44100 samples / sec ) default
  
      outputFileDesc.mSampleRate = self.samplingRate;
      outputFileDesc.mFormatID = kAudioFormatLinearPCM;
      outputFileDesc.mFormatFlags = kAudioFormatFlagIsFloat;
      outputFileDesc.mBytesPerPacket = 4*self.numChannels;
      outputFileDesc.mFramesPerPacket = 1;
      outputFileDesc.mBytesPerFrame = 4*self.numChannels;
      outputFileDesc.mChannelsPerFrame = self.numChannels;
      outputFileDesc.mBitsPerChannel = 32;
  
      CheckError(ExtAudioFileCreateWithURL(audioFileRef, kAudioFileWAVEType, &amp;outputFileDesc, NULL, kAudioFileFlags_EraseFile, &amp;_outputFile), "Creating file");
  </code></pre>
  
  <p>.
  .
  .</p>