＆＃x3010; ios＆＃x3011;监视卷键，导致多个调用

发布于 2025-02-04 09:25:55 字数 750 浏览 0 评论 0原文

我想通过单击“音量”按钮来进行一些操作。我可以通过以下方式做到这一点

 [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(volumeChangeNotification:)name:@"SystemVolumeDidChange" object:nil];

 - (void)volumeChangeNotification:(NSNotification *)notification {
  //do something
 }

，但我发现了一个令人困惑的现象。单击卷键一次，监视事件将被调用两次。我尝试在侦听器函数末尾删除侦听器，这样

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(volumeChangeNotification:)name:@"SystemVolumeDidChange" object:nil];

- (void)volumeChangeNotification:(NSNotification *)notification {
//do something
[[NSNotificationCenter defaultCenter] removeObserver:self name:@"SystemVolumeDidChange" object:nil];
}

，我在1秒钟后打开监视器，但这也行不通。我该怎么办？非常感谢

原文

I want to do some operations by clicking the volume button. I can do this in the following ways

 [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(volumeChangeNotification:)name:@"SystemVolumeDidChange" object:nil];

 - (void)volumeChangeNotification:(NSNotification *)notification {
  //do something
 }

But I found a puzzling phenomenon. Click the volume key once, and the monitoring event will be called twice. I try to delete the listener at the end of the listener function ，like this

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(volumeChangeNotification:)name:@"SystemVolumeDidChange" object:nil];

- (void)volumeChangeNotification:(NSNotification *)notification {
//do something
[[NSNotificationCenter defaultCenter] removeObserver:self name:@"SystemVolumeDidChange" object:nil];
}

Then I turn on the monitor after 1 second, but it also doesn't work. What should I do？thanks verymuch

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