改变iOS音频播放器的音高 - 像Alvin和花栗鼠

我在StackOverflow中找到了这段代码片段。我认为这就是我想要使用的。但我不能让它改变音调 - 就像我预期的那样。我认为改变44100.0上/下会影响音高。但无论setValue如何，我都没有变化。

I found this code fragment in StackOverflow. I think this is what I want to use. But I cannot get it to change the pitch—as I expected it to. I figured changing the 44100.0 up/down would affect the pitch. But I'm getting no change, regardless of the setValue.

NSMutableDictionary *settings = [[NSMutableArray alloc] init];    
[settings setValue: [NSNumber numberWithFloat:44100.0] forKey:AVSampleRate];

显然我遗漏了一些东西。

Clearly I'm missing something.

可以提供更多上下文的任何其他片段吗？

Any additional fragments available to give this some more context?