随笔-app音量slider与系统音量统一同步

   用到了音量跟系统设备的音量要同步，随手整理一下。

   导入框架：<MPMusicPlayerController.framework>

   

#import <MediaPlayer/MediaPlayer.h>

    注册通知：

- (void)viewDidLoad {
    //系统音量变化时，调整volumeSlider 的值
 

    MPMusicPlayerController *MPMusciPlayer = [MPMusicPlayerController applicationMusicPlayer];
    [MPMusciPlayer beginGeneratingPlaybackNotifications];
    [[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(changeVolumeSlider)
                                                 name:MPMusicPlayerControllerVolumeDidChangeNotification
                                               object:nil];

}

实现代理方法：

//音量按钮
- (IBAction)slidervaluechange:(UISlider *)sender {
    MPMusicPlayerController *mp=[MPMusicPlayerController applicationMusicPlayer];
    mp.volume=self.yinliangslider.value;

    
}

实现通知方法changeVolumeSlider:

-(void)changeVolumeSlider{
    self.yinliangslider.value = [[MPMusicPlayerController applicationMusicPlayer] volume];
}

到这里就OK了，三部曲 is so easy!