iOS监听设备音量变化

iOS设备如何监听音量变化呢？

iOS15 停止触发SystemVolumeDidChangeNotification

1、在使用该功能的地方添加通知AVSystemController_SystemVolumeDidChangeNotification

- (void)addVolumeNotification
    AVAudioSession *session = [AVAudioSession sharedInstance];
    [session setActive:YES error:nil];
    [UIApplication.sharedApplication beginReceivingRemoteControlEvents];
    [NSNotificationCenter.defaultCenter addObserver:self selector:@selector(volumeChangeNotification:) name:@"AVSystemController_SystemVolumeDidChangeNotification" object:nil];
}

- (void)volumeChangeNotification:(NSNotification *)noti {
    NSDictionary *userInfo = noti.userInfo;
    NSString *value = [userInfo valueForKey:@"AVSystemController_AudioVolumeChangeReasonNotificationParameter"];
    if ([value isEqualToString:@"ExplicitVolumeChange"]) {
        NSLog(@"ExplicitVolumeChange");
    }
}

不用时候要移除通知

- (void)removeVolumeNofication {
    [UIApplication.sharedApplication endReceivingRemoteControlEvents];
    [NSNotificationCenter.defaultCenter removeObserver:self name:@"AVSystemController_SystemVolumeDidChangeNotification" object:nil];
}

2、但是在使用过程中，设备升级到iOS 15.0及以后版本，发现AVSystemController_SystemVolumeDidChangeNotification通知不触发；可以使用KVC方法替换，实现相应的功能。

- (void)addVolumeKVC {
    AVAudioSession *session = [AVAudioSession sharedInstance];
    [session setActive:YES error:nil];
    [session addObserver:self forKeyPath:@"outputVolume" options:NSKeyValueObservingOptionNew context:nil];
}

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context {
    if ([keyPath isEqual:@"outputVolume"]) {
        NSLog(@"%@", change);
    }
}

记得不需要时候移除哦！

- (void)removeVolumeKVC {
    [UIApplication.sharedApplication endReceivingRemoteControlEvents];
    [AVAudioSession.sharedInstance removeObserver:self forKeyPath:@"outputVolume" context:nil];
}

备注：如果有更好的方法欢迎评论学习！