January 2020
Intermediate to advanced
356 pages
6h 4m
Chinese
Content preview from Swift游戏开发经典实例
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声音
｜
145
MPMediaPickerController
的取消按钮之后，委托对象的
mediaPickerDidCancel
方法会被触发，我们同样需要在这个方法中调用同样的方法关闭
MPMediaPickerController
。
4.10
当其他
App
正在播放音乐时的操作
问题
有时候，我们想让游戏的背景音乐只在用户没有播放其他声音时播放。
解决方案
我们可以用
AVAudioSession
类来检查当前是否有其他应用程序在播放音乐：
let session = AVAudioSession.sharedInstance()
if (session.isOtherAudioPlaying) {
//
当前有其他应用程序在播放声音。这种情况下，就不能再播放任何
//
声音了（比如你的背景音乐），以免声音混杂在一起
} else {
//
当前没有其他应用程序在播放，开始播放！
}
讨论
AVAudioSession
类允许我们对设备中的声音该如何播放进行一些控制，以及设备
如何处理某些事情，例如，振铃开关（这个开关位于设备的侧边）以及用户锁屏时
进行一些非常灵活地控制。
正常情况下，当我们开始用
AVAudioPlayer
回放音乐时，如果当前有其他
App
（如
系统内置的音乐
App
）正在播放，则其他
App
应当停止播放，而只有我们游戏中
的播放器可以发声。
当然，我们也可以让用户在玩游戏的时候仍然继续听他自己的音乐，例如，当这个
游戏中的背景音乐不是非常重要的时候。
为了改变默认的让其他应用程序停止播放的设置，我们需要修改 ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.