在ios6以前，我们有如下的方法：
#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。
