iOS中的AVSpeechSynthesizer可以很輕松的實現實現文本到語音的功能，基本代碼如下:

    self.speechSynthesizer = [[AVSpeechSynthesizer alloc] init];
    AVSpeechUtterance *utterance = [AVSpeechUtterance speechUtteranceWithString:@"FlyElephant"];
    
    AVSpeechSynthesisVoice *voiceType = [AVSpeechSynthesisVoice voiceWithLanguage:@"en-US"];
    utterance.voice = voiceType;
    //設置語速
    utterance.rate *= 0.5;
    //設置音量
    utterance.volume = 0.6;

    [self.speechSynthesizer speakUtterance:utterance];

AVSpeechUtterance可以設置對應的語言，如果設置的語言不能識別文本不能生成語音播放，蘋果支持的語言如下:

• Arabic (ar-SA)
• Chinese (zh-CN, zh-HK, zh-TW)
• Czech (cs-CZ)
• Danish (da-DK)
• Dutch (nl-BE, nl-NL)
• English (en-AU, en-GB, en-IE, en-US, en-ZA)
• Finnish (fi-FI)
• French (fr-CA, fr-FR)
• German (de-DE)
• Greek (el-GR)
• Hebrew (he-IL)
• Hindi (hi-IN)
• Hungarian (hu-HU)
• Indonesian (id-ID)
• Italian (it-IT)
• Japanese (ja-JP)
• Korean (ko-KR)
• Norwegian (no-NO)
• Polish (pl-PL)
• Portuguese (pt-BR, pt-PT)
• Romanian (ro-RO)
• Russian (ru-RU)
• Slovak (sk-SK)
• Spanish (es-ES, es-MX)
• Swedish (sv-SE)
• Thai (th-TH)
• Turkish (tr-TR)

以上就是蘋果支持的語言編碼，當然你也可以通過speechVoices遍歷對應的語言編碼:

    NSArray *voice = [AVSpeechSynthesisVoice speechVoices];
    for (AVSpeechSynthesisVoice *voiceModel in voice) {
        NSLog(@"FlyElephant-%@",voiceModel);
    }