判断是否插入了耳机

#import <AVFoundation/AVFoundation.h>  
  
- (BOOL)isHeadphonePluggedIn {  

    AVAudioSessionRouteDescription *route = [[AVAudioSession sharedInstance] currentRoute];  
    for (AVAudioSessionPortDescription *desc in [route outputs]) {  
        if ([[desc portType] isEqualToString:AVAudioSessionPortHeadphones])  
            return YES;  
    }  
    return NO;  

}