iOS-设置系统音量及监听

1.设置系统音量
<pre><code>`

MPVolumeView *volumeView = [MPVolumeView new];
volumeView.showsRouteButton = NO;
volumeView.showsVolumeSlider = NO;
[self.view addSubview:volumeView];
__weak __typeof(self)weakSelf = self;
[[volumeView subviews] enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
    if ([obj isKindOfClass:[UISlider class]]) {
        __strong __typeof(weakSelf)strongSelf = weakSelf;
        strongSelf.volumeSlider = obj;
        *stop = YES;
    }
}];
[self.volumeSlider setValue:1.0 animated:YES];`</code></pre>

2.注册通知

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

3.监听通知

<pre><code>-(void)volumeChanged:(NSNotification *)notification{ float volume = [[[notification userInfo] objectForKey:@"AVSystemController_AudioVolumeNotificationParameter"] floatValue]; NSLog(@"FlyElephant-系统音量:%f", volume); }</code></pre>

4.移除通知

[[NSNotificationCenter defaultCenter] removeObserver:self name:@"AVSystemController_SystemVolumeDidChangeNotification" object:nil];