-(void)whetherTheHeadsetInsert{
  [[AVAudioSession sharedInstance] setActive:YES error:nil];
//創(chuàng)建單例對象并且使其設置為活躍狀態(tài).
  [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(audioRouteChangeListenerCallback:)   name:AVAudioSessionRouteChangeNotification object:nil];//設置通知
}
//通知方法的實現(xiàn)
- (void)audioRouteChangeListenerCallback：(NSNotification*)notification {
  NSDictionary *interuptionDict = notification.userInfo;
  NSInteger routeChangeReason = [[interuptionDict valueForKey:AVAudioSessionRouteChangeReasonKey] integerValue];
  switch (routeChangeReason) {

      case AVAudioSessionRouteChangeReasonNewDeviceAvailable:
          NSLog(@"AVAudioSessionRouteChangeReasonNewDeviceAvailable");
          NSLog(@"耳機插入");
          break;
      case AVAudioSessionRouteChangeReasonOldDeviceUnavailable:
          NSLog(@"AVAudioSessionRouteChangeReasonOldDeviceUnavailable");
          NSLog(@"耳機拔出");
          break;
          
      case AVAudioSessionRouteChangeReasonCategoryChange:            // called at start - also when other audio wants to play
          NSLog(@"AVAudioSessionRouteChangeReasonCategoryChange");
          break;
  }
}