我怎样才能淡出由MPMusicPlayerController播放的声音？

问题描述

我想淡出在特定时间内通过 MPMusicPlayerController 播放的声音？ 我怎样才能做到这一点？

I'd like to fade-out the sound played by MPMusicPlayerController over a particular time period? How can I do this?

推荐答案

有没有褪色的功能，所以你必须自己实现它。循环，直到体积为0，并添加一个延迟每个步骤。如果你想这一切都为2秒发生的未来，把code块上：

There is no fade functionality so you have to implement it yourself. Loop until volume is 0, and add a delay for each step. If you want all this to happen 2 seconds into the future, put the code on a block:

MPMusicPlayerController *iPod = [MPMusicPlayerController iPodMusicPlayer];

int64_t delay = 2LL * NSEC_PER_SEC;
dispatch_after(dispatch_time(DISPATCH_TIME_NOW,delay), dispatch_get_current_queue(), ^{
    while (iPod.volume>.1){
        iPod.volume -= .1;
        [NSThread sleepForTimeInterval:0.1];
    }
});

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