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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136
｜
第
4
章
当代码运行时，
for
循环创建了许多
dispatch
去设定
AVAudioPlayer
的音量，每个
dispatch
都会让音量变小一点。这将导致用户听到的声音音量会逐渐变小，最终得
到了一个声音淡出的效果！
4.5
合成语音
问题
如何让
App
学会说话？
解决方案
首先，在代码中导入
AVFoundation
（参考
4.1
节的问题）。
然后创建一个
AVSpeechSynthesizer
对象：
var speechSynthesizer = AVSpeechSynthesizer()
想要让某段文本被合成，我们需要用到
AVSpeechUtterance
对象：
let utterance = AVSpeechUtterance(string: textToSpeak)
然后将
utterance
传递给
AVSpeechSynthesizer
对象：
self.speechSynthesizer.speak (utterance)
讨论
AVSpeechSynthesizer
、
Siri
个人助手以及
Voice Over
使用的是相同的语音。从
iPhone4S
开始，所有的
iOS
设备都内置了
Siri
。
我们可以向一个
AVSpeechSynthesizer
一次性发送多个
AVSpeechUtterance
。如果
在调用
speakUtterance
的时候合成器正在发声，则合成器会等当前的
utterance
念
完之后才会说下一句。
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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.
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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.