使用nsuserdefaults关闭声音效果

我试图关闭我的应用程序上的声音效果

播放方法为“[我的音乐播放];

-(void)viewDidLoad {
     BOOL soundIsOff = [defaults boolForKey:@"sound_off"];
     //the problem is here 
     //xcode compiler doesn't copile this code 
     [myMusic play] = soundIsOff;

}

声音代码: ’ ///音效

 NSString * musicSonati = [[NSBundle mainBundle] pathForResource:@"sound"      ofType:@"wav"];
 myMusic = [[AVAudioPlayer alloc] initWithContentsOfURL:[NSURL     fileURLWithPath:musicSonati] error:NULL];
 myMusic.delegate = self;
 myMusic.numberOfLoops = 0;

Shake API代码:

- (void)motionEnded:(UIEventSubtype)motion withEvent:(UIEvent *)event {

 if (event.subtype == UIEventSubtypeMotionShake)

  //Play sound :
  [myMusic play] ; 
 }
}