AVSpeechSynthesizer详解

介绍
从IOS5开始，IOS系统已经在siri上集成了语音合成的功能，但是是私有API。但是在IOS7，新增了一个简单的API----AVSpeechSynthesizer来做这件事情。

案列如下：

#import "SpeechSynthesisViewController.h"
#import
@property (nonatomic, strong) AVSpeechSynthesizer *synthesizer;

@implementation SpeechSynthesisViewController
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
    }
    return self;
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    self.synthesizer = [[AVSpeechSynthesizer alloc] init];
}

- (IBAction)say 
{

     AVSpeechUtterance *utterance = [AVSpeechUtterance speechUtteranceWithString:"iOS7新特性"];
    //设置语言类别（ 不能被识别，返回值为nil）
    AVSpeechSynthesisVoice *voiceType = [AVSpeechSynthesisVoice voiceWithLanguage:@"zh-CN"];
    utterance.voice =  voiceType;
    //设置语速快慢
    utterance.rate *= 0.5;
   // 语音合成器会生成音频
    [self.synthesizer speakUtterance:utterance];

}

语言类别
IOS7包含了一组可以用来合成的声音的嗓音，你可以自定义多种嗓音来合成。 
"[AVSpeechSynthesisVoice 0x978a0b0] Language: th-TH", 
"[AVSpeechSynthesisVoice 0x977a450] Language: pt-BR", 
"[AVSpeechSynthesisVoice 0x977a480] Language: sk-SK",
"[AVSpeechSynthesisVoice 0x978ad50] Language: fr-CA", 
"[AVSpeechSynthesisVoice 0x978ada0] Language: ro-RO", 
"[AVSpeechSynthesisVoice 0x97823f0] Language: no-NO",
"[AVSpeechSynthesisVoice 0x978e7b0] Language: fi-FI", 
"[AVSpeechSynthesisVoice 0x978af50] Language: pl-PL", 
"[AVSpeechSynthesisVoice 0x978afa0] Language: de-DE", 
"[AVSpeechSynthesisVoice 0x978e390] Language: nl-NL", 
"[AVSpeechSynthesisVoice 0x978b030] Language: id-ID", 
"[AVSpeechSynthesisVoice 0x978b080] Language: tr-TR", 
"[AVSpeechSynthesisVoice 0x978b0d0] Language: it-IT", 
"[AVSpeechSynthesisVoice 0x978b120] Language: pt-PT",
"[AVSpeechSynthesisVoice 0x978b170] Language: fr-FR",
"[AVSpeechSynthesisVoice 0x978b1c0] Language: ru-RU", 
"[AVSpeechSynthesisVoice 0x978b210]Language: es-MX", 
"[AVSpeechSynthesisVoice 0x978b2d0] Language: zh-HK",
"[AVSpeechSynthesisVoice 0x978b320] Language: sv-SE", 
"[AVSpeechSynthesisVoice 0x978b010] Language: hu-HU",
"[AVSpeechSynthesisVoice 0x978b440] Language: zh-TW",
"[AVSpeechSynthesisVoice 0x978b490] Language: es-ES",
"[AVSpeechSynthesisVoice 0x978b4e0] Language: zh-CN", 
"[AVSpeechSynthesisVoice 0x978b530] Language: nl-BE", 
"[AVSpeechSynthesisVoice 0x978b580] Language: en-GB",
"[AVSpeechSynthesisVoice 0x978b5d0] Language: ar-SA", 
"[AVSpeechSynthesisVoice 0x978b620] Language: ko-KR",
"[AVSpeechSynthesisVoice 0x978b670] Language: cs-CZ",
"[AVSpeechSynthesisVoice 0x978b6c0] Language: en-ZA", 
"[AVSpeechSynthesisVoice 0x978aed0] Language: en-AU",
"[AVSpeechSynthesisVoice 0x978af20] Language: da-DK",
"[AVSpeechSynthesisVoice 0x978b810] Language: en-US",
"[AVSpeechSynthesisVoice 0x978b860] Language: en-IE",
"[AVSpeechSynthesisVoice 0x978b8b0] Language: hi-IN", 
"[AVSpeechSynthesisVoice 0x978b900] Language: el-GR",
"[AVSpeechSynthesisVoice 0x978b950] Language: ja-JP" 

总结
在IOS7，语音合成器非常简单，多语言方便使用，可以提高应用的访问性，而不用时刻用你的手和眼来操作应用。