iPhone - 捕获设备按钮按下 [英] iPhone - Capture device button push

问题描述

我知道您无法在应用程序中控制设备音量，但我希望设备音量能够影响我在应用程序中控制音量的UIScrollBar。

I know you cannot control device volume from within your application, but I would like the device volume to be able to affect the UIScrollBar I have in my application to control volume.

我知道这是可能的，因为Last.fm应用程序会这样做，我想实现这种行为。

I know this is possible because the Last.fm application does it, I would like to implement this behaviour.

我几乎找不到关于互联网的信息。这里的任何人都可以帮助我吗？ ：）

I can find very little information on the interwebs. Anyone here can help me maybe? :)

推荐答案

听众回调很容易

void audioVolumeChangeListenerCallback (void *inUserData, AudioSessionPropertyID inID, UInt32 inDataSize, const void *inData)
{
    RootViewController *controller = (RootViewController *) inUserData;
    Float32 newGain = *(Float32 *)inData;
    [controller setGainManual:newGain]; 
}

在我的视图控制器的viewDidLoad中初始化，如下所示

which gets initialized in my view controller's viewDidLoad like this

AudioSessionAddPropertyListener (kAudioSessionProperty_CurrentHardwareOutputVolume ,audioVolumeChangeListenerCallback, self );

这也是所有SDK / App Store友好的。

This is all SDK/App Store friendly too.

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