ios - 通知中心不调用选择器方法帮帮我

Question

- (IBAction)playOrPauseSound:(id)sender;
{ 
    [_audioPlayer play];
    [[NSNotificationCenter defaultCenter] addObserver:_audioPlayer selector:@selector(nextsong:) name:AVPlayerItemDidPlayToEndTimeNotification object:nil];
}

- (IBAction)nextsong:(id)sender {
    //code 
}

Answer 1

您应该将 notificationObserver 设置为，self因为这是充当观察者的对象。您还应该将 notificationSender 设置为，_audioPlayer因为这是发送AVPlayerItemDidPlayToEndTimeNotification通知的对象。

此外，选择器方法应该有一个 NSNotification 实例作为唯一参数。所以我很想创建一个单独的方法来处理接收通知，然后调用 next song 方法，也许：

- (void)receivedNextSongNotification:(NSNotification *)notification 
{
    [self nextsong:nil];
}

所以总的来说，是这样的：

- (IBAction)playOrPauseSound:(id)sender
{ 
    [_audioPlayer play]; 
    [[NSNotificationCenter defaultCenter] addObserver: self //will look for the selector in the current class
                                             selector: @selector(playerItemDidPlayToEndTime:) 
                                                 name: AVPlayerItemDidPlayToEndTimeNotification 
                                               object: _audioPlayer]; // the object that sends the notifications
}

- (void)playerItemDidPlayToEndTime:(NSNotification *)notification 
{
    [self nextsong:nil];
}

- (IBAction)nextsong:(id)sender 
{
    //code  
}

还要确保在调用removeObserver:name:object:之前self或被_audioPlayer释放。

希望有帮助。