#import<AVFoundation/AVFoundation.h>

 

    [[AVAudioSession sharedInstance] setDelegate:self];

  AudioSessionAddPropertyListener(kAudioSessionProperty_AudioRouteChange,audioRouteChangeListenerCallback, self);

然后实现该回调：

//音频监控回调函数

static void audioRouteChangeListenerCallback (void                      *inUserData,

                                              AudioSessionPropertyID    inPropertyID,

                                              UInt32                    inPropertyValueSize,

                                              constvoid                *inPropertyValue

                                              )

{

    if (inPropertyID !=kAudioSessionProperty_AudioRouteChange)

    {

        return;

    }

    // Determines the reason for the route change, to ensure that it is not

    // because of a category change.

    

    CFDictionaryRef routeChangeDictionary = inPropertyValue;

    CFNumberRef     routeChangeReasonRef = CFDictionaryGetValue (routeChangeDictionary, CFSTR (kAudioSession_AudioRouteChangeKey_Reason));

    SInt32          routeChangeReason;

    CFNumberGetValue (routeChangeReasonRef,kCFNumberSInt32Type, &routeChangeReason);

//  do your handling here

}

请注意[[AVAudioSession sharedInstance] setDelegate:self]一定不要遗漏，否则该回调应该无法触发。

    [[NSNotificationCenterdefaultCenter] addObserver:selfselector:@selector(outputDeviceChanged:)name:AVAudioSessionRouteChangeNotificationobject:[AVAudioSessionsharedInstance]];

- (void)outputDeviceChanged:(NSNotification *)aNotification

{

 // do your jobs here

}

请注意，addobserver的参数填写：其中的object必须是[AVAudioSession sharedInstance]，而不是我们通常很多情况下填写的nil，此处若为nil，通知也不会触发。