Ios 当我多次进入AVAudioPlayer的视图控制器时，AVAudioPlayer会播放上面的内容

我有一个问题，我正在视图控制器appMusicViewController中播放AVAudioPlayer，我将会话设置为AVAudioSessionCategorySoloAmbient，它运行良好，当我导航到其他视图时，背景中的边界音乐会响，但当我回到appMusicViewController并触摸播放按钮时，它不会停止最后一次播放，所以它同时播放音乐。appMusicViewController如何知道上次分配的AVAudioPlayer的信息

-(void)viewDidLoad 
{

[super viewDidLoad];

playList=[[NSArray alloc] initWithObjects:@"David Keller - Klangkissen (Extended       Version)",@"Karmon - Wowshit (Original Mix) HQ",@"Phonique - Feel What You Want Feat.  Rebecca",@"Toky - About You (Original Mix)", nil]; // 4 SONGS
[[AVAudioSession sharedInstance] setCategory: AVAudioSessionCategorySoloAmbient error: nil];

artWork=[[NSArray alloc] initWithObjects:@"David Keller - Klangkissen (Extended Version).jpg",@"Karmon - Wowshit (Original Mix) HQ.jpg",@"Phonique - Feel What You Want Feat. Rebecca.jpg",@"Toky - About You (Original Mix).jpg", nil];


NSString *soundFilePath = [[NSBundle mainBundle] pathForResource:[playList objectAtIndex:count] ofType: @"mp3"];
NSURL *fileURL = [[NSURL alloc] initFileURLWithPath:soundFilePath ];
myAudioPlayer = [[AVAudioPlayer alloc] initWithContentsOfURL:fileURL error:nil];


myAudioPlayer.numberOfLoops=0;
myAudioPlayer.delegate=self;

myAudioPlayer.volume=self.volume.maximumValue/2;
}

- (IBAction)play:(id)sender
{

[myAudioPlayer play];
playing=YES;


}