Mac上的简单音频输入API？

#import<Foundation/Foundation.h>
#import <CoreAudio/CoreAudio.h>

@interface AudioInput : NSObject
{
    AudioUnit audioUnit;
    BOOL isRunning;
}

- (void)start;
- (void)stop;

@end

@implementation AudioInput

- (id)init
{
    self = [super init];
    if (self) {
        // Initialize the audio unit
        AudioComponentDescription desc;
        desc.componentType = kAudioUnitType_Output;
        desc.componentSubType = kAudioUnitSubType_RemoteIO;
        desc.componentManufacturer = kAudioUnitManufacturer_Apple;
        desc.componentFlags = 0;
        desc.componentFlagsMask = 0;
        
        AudioComponent comp = AudioComponentFindNext(NULL, &desc);
        AudioComponentInstanceNew(comp, &audioUnit);
        
        // Set up the audio unit
        UInt32 enableInput = 1;
        AudioUnitSetProperty(audioUnit, kAudioOutputUnitProperty_EnableIO, kAudioUnitScope_Input, 1, &enableInput, sizeof(enableInput));
        
        UInt32 enableOutput = 0;
        AudioUnitSetProperty(audioUnit, kAudioOutputUnitProperty_EnableIO, kAudioUnitScope_Output, 0, &enableOutput, sizeof(enableOutput));
        
        AudioStreamBasicDescription format;
        format.mSampleRate = 44100.0;
        format.mFormatID = kAudioFormatLinearPCM;
        format.mFormatFlags = kAudioFormatFlagsNativeEndian | kAudioFormatFlagIsPacked | kAudioFormatFlagIsFloat;
        format.mBytesPerPacket = 4;
        format.mFramesPerPacket = 1;
        format.mBytesPerFrame = 4;
        format.mChannelsPerFrame = 1;
        format.mBitsPerChannel = 32;
        format.mReserved = 0;
        
        AudioUnitSetProperty(audioUnit, kAudioUnitProperty_StreamFormat, kAudioUnitScope_Input, 1, &format, sizeof(format));
        AudioUnitSetProperty(audioUnit, kAudioUnitProperty_StreamFormat, kAudioUnitScope_Output, 0, &format, sizeof(format));
        
        // Set up the callback
        AURenderCallbackStruct input;
        input.inputProc = AudioInputCallback;
        input.inputProcRefCon = (__bridge void *)self;
        AudioUnitSetProperty(audioUnit, kAudioOutputUnitProperty_SetInputCallback, kAudioUnitScope_Global, 1, &input, sizeof(input));
        
        // Initialize the audio unit
        AudioUnitInitialize(audioUnit);
    }
    return self;
}

- (void)start
{
    if (!isRunning) {
        AudioOutputUnitStart(audioUnit);
        isRunning = YES;
    }
}

- (void)stop
{
    if (isRunning) {
        AudioOutputUnitStop(audioUnit);
        isRunning = NO;
    }
}

static OSStatus AudioInputCallback(void *inRefCon, AudioUnitRenderActionFlags *ioActionFlags, const AudioTimeStamp *inTimeStamp, UInt32 inBusNumber, UInt32 inNumberFrames, AudioBufferList *ioData)
{
    AudioInput *self = (__bridge AudioInput *)inRefCon;
    
    // Handle the input data
    // ...
    
    return noErr;
}

@end