之前 AudioSessionGetProperty(kAudioSessionProperty_AudioRoute, &propertySize, &route); 的方法在 ios7之后被禁用了，现在有新的方法来检测iOS设备是否插入耳机：

 1 -(BOOL)hasHeadset
 2 {
 3     AVAudioSession *audioSession = [AVAudioSession sharedInstance];
 4     
 5     AVAudioSessionRouteDescription *currentRoute = [audioSession currentRoute];
 6     
 7     for(AVAudioSessionPortDescription *output in currentRoute.outputs)
 8     {
 9         if([[output portType] isEqualToString:AVAudioSessionPortHeadphones])
10         {
11             return YES;
12         }
13     
14     }
15     
16      return NO;
17 
18 }