How to generate audio wave form programmatically while recording Voice in iOS?

Question

How to generate audio wave form programmatically while recording Voice in iOS?

Answer 1

You should check out EZAudio (https://github.com/syedhali/EZAudio), specifically the EZRecorder and the EZAudioPlot (or GPU-accelerated EZAudioPlotGL).

There is also an example project that does exactly what you want, https://github.com/syedhali/EZAudio/tree/master/EZAudioExamples/iOS/EZAudioRecordExample

EDIT: Here's the code inline

/// In your interface

/**
 Use a OpenGL based plot to visualize the data coming in
 */
@property (nonatomic,weak) IBOutlet EZAudioPlotGL *audioPlot;
/**
 The microphone component
 */
@property (nonatomic,strong) EZMicrophone *microphone;
/**
 The recorder component
 */
@property (nonatomic,strong) EZRecorder *recorder;

...

/// In your implementation

// Create an instance of the microphone and tell it to use this view controller instance as the delegate
-(void)viewDidLoad {
    self.microphone = [EZMicrophone microphoneWithDelegate:self startsImmediately:YES];
}

// EZMicrophoneDelegate will provide these callbacks
-(void)microphone:(EZMicrophone *)microphone
 hasAudioReceived:(float **)buffer
   withBufferSize:(UInt32)bufferSize
withNumberOfChannels:(UInt32)numberOfChannels {
  dispatch_async(dispatch_get_main_queue(),^{
    // Updates the audio plot with the waveform data
    [self.audioPlot updateBuffer:buffer[0] withBufferSize:bufferSize];
  });
}

-(void)microphone:(EZMicrophone *)microphone hasAudioStreamBasicDescription:(AudioStreamBasicDescription)audioStreamBasicDescription {
  // The AudioStreamBasicDescription of the microphone stream. This is useful when configuring the EZRecorder or telling another component what audio format type to expect.

  // We can initialize the recorder with this ASBD
  self.recorder = [EZRecorder recorderWithDestinationURL:[self testFilePathURL]
                                         andSourceFormat:audioStreamBasicDescription];

}

-(void)microphone:(EZMicrophone *)microphone
    hasBufferList:(AudioBufferList *)bufferList
   withBufferSize:(UInt32)bufferSize
withNumberOfChannels:(UInt32)numberOfChannels {

  // Getting audio data as a buffer list that can be directly fed into the EZRecorder. This is happening on the audio thread - any UI updating needs a GCD main queue block. This will keep appending data to the tail of the audio file.
  if( self.isRecording ){
    [self.recorder appendDataFromBufferList:bufferList
                             withBufferSize:bufferSize];
  }

}