效果图，图片找的网上的

一：写在前面

相关源代码已经上传到网上，里面该有的注释也都有了，感兴趣的同学可以直接上Github下载： AVFoundation相关代码下载地址：点击我就可以了。

二：正文

我们有时候在读书软件上可以发现语音朗读功能（读起来好像没什么感情）。其实这个利用iOS系统api就可以实现。下面就通过一个语音朗读文字的demo来讲解该功能的实现步骤。

2.1：AVSpeechSynthesizer介绍

实现该功能核心的部件就是AVSpeechSynthesizer。

NS_CLASS_AVAILABLE_IOS(7_0)
@interface AVSpeechSynthesizer : NSObject

大家看到了么，iOS7.0之后才出现了AVSpeechSynthesizer。AVSpeechSynthesizer具有以下属性：

//代理方法
@property(nonatomic, weak, nullable) id<AVSpeechSynthesizerDelegate> delegate;
//是否正在朗读（只读）
@property(nonatomic, readonly, getter=isSpeaking) BOOL speaking;
//是否已经暂停(只读)
@property(nonatomic, readonly, getter=isPaused) BOOL paused;

支持的方法如下：

//朗读方法，需要一个AVSpeechUtterance类型参数
- (void)speakUtterance:(AVSpeechUtterance *)utterance;

//停止朗读，会清理掉当前正在执行朗读操作的队列    
- (BOOL)stopSpeakingAtBoundary:(AVSpeechBoundary)boundary;
//暂停朗读，这里面需要传递一个AVSpeechBoundary类型参数，两种选择，是立即停止还是读完这个单词再停止。
- (BOOL)pauseSpeakingAtBoundary:(AVSpeechBoundary)boundary;
//继续朗读
- (BOOL)continueSpeaking;

上面提到代理方法，还记得不？下面就是相关的代理方法：

//开始朗读的代理方法
- (void)speechSynthesizer:(AVSpeechSynthesizer *)synthesizer didStartSpeechUtterance:(AVSpeechUtterance *)utterance;
//结束朗读的代理方法
- (void)speechSynthesizer:(AVSpeechSynthesizer *)synthesizer didFinishSpeechUtterance:(AVSpeechUtterance *)utterance;
//暂停朗读的代理方法
- (void)speechSynthesizer:(AVSpeechSynthesizer *)synthesizer didPauseSpeechUtterance:(AVSpeechUtterance *)utterance;
//继续朗读的代理方法
- (void)speechSynthesizer:(AVSpeechSynthesizer *)synthesizer didContinueSpeechUtterance:(AVSpeechUtterance *)utterance;
- (void)speechSynthesizer:(AVSpeechSynthesizer *)synthesizer didCancelSpeechUtterance:(AVSpeechUtterance *)utterance;
////将要播放的语音文字代理方法
- (void)speechSynthesizer:(AVSpeechSynthesizer *)synthesizer willSpeakRangeOfSpeechString:(NSRange)characterRange utterance:(AVSpeechUtterance *)utterance;

2.2：AVSpeechUtterance介绍

除了核心的AVSpeechSynthesizer，还有一个非常关键的成员就是AVSpeechUtterance，要是想把声音读出来并且设置和声音有关的一些属性，你离不开它。AVSpeechUtterance主要包含以下属性：

//需要用什么语言来朗读，系统提供了很多语言选项，如果有中文，一定要选择中文语言，要不然读不出来。
@property(nonatomic, retain, nullable) AVSpeechSynthesisVoice *voice;
//朗读的内容
@property(nonatomic, readonly) NSString *speechString;
//朗读的内容NSAttributedString 格式
@property(nonatomic, readonly) NSAttributedString *attributedSpeechString API_AVAILABLE(ios(10.0), watchos(3.0), tvos(10.0));

/* Setting these values after a speech utterance has been enqueued will have no effect. */
////语速0.0f~1.0f
@property(nonatomic) float rate;             // Values are pinned between AVSpeechUtteranceMinimumSpeechRate and AVSpeechUtteranceMaximumSpeechRate.
 //声音的音调0.5f~2.0f
@property(nonatomic) float pitchMultiplier;  // [0.5 - 2] Default = 1
@property(nonatomic) float volume;           // [0-1] Default = 1
//播放下下一句话的时候有多长时间的延迟
@property(nonatomic) NSTimeInterval preUtteranceDelay;    // Default is 0.0
//开始播放之前需要等待多久
@property(nonatomic) NSTimeInterval postUtteranceDelay;   // Default is 0.0

支持的方法如下：

//初始化类方法，需要传一个字符串进去
+ (instancetype)speechUtteranceWithString:(NSString *)string;
 //初始化类方法，需要一个NSAttributedString类型字符串
+ (instancetype)speechUtteranceWithAttributedString:(NSAttributedString *)string API_AVAILABLE(ios(10.0), watchos(3.0), tvos(10.0));

//初始化对象方法，需要一个字符串作为参数
- (instancetype)initWithString:(NSString *)string;
//初始化对象方法，需要一个NSAttributedString类型字符串
- (instancetype)initWithAttributedString:(NSAttributedString *)string API_AVAILABLE(ios(10.0), watchos(3.0), tvos(10.0));

上面提到的语言类型，主要由以下几种：

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)

三：代码实现：

相关知识点介绍完毕之后，下面就是具体的代码实现：

#import "ViewController.h"
#import <AVFoundation/AVFoundation.h>
@interface ViewController ()<AVSpeechSynthesizerDelegate>
@property(nonatomic,strong) NSArray * strArray;
@property(nonatomic,strong) NSArray *voiceArray;
@property(nonatomic,strong) AVSpeechSynthesizer *synthesizer;
@property (weak, nonatomic) IBOutlet UILabel *speechLabel;
@property (weak, nonatomic) IBOutlet UIButton *controlButton;
@property (nonatomic,assign)BOOL isPlay;
@end

@implementation ViewController

- (void)viewDidLoad {
[super viewDidLoad];
self.strArray =@[@"单车欲问边，",
                 @"属国过居延。",
                 @"征蓬出汉塞，",
                 @"归雁入胡天。",
                 @"大漠孤烟直，",
                 @"长河落日圆，",
                 @"萧关逢候骑，",
                 @"都护在燕然。",
                 @"A solitary carriage to the frontiers bound,",
                 @"An envoy with no retinue around,",
                 @"A drifting leaf from proud Cathy,",
                 @"With geese back north on a hordish day.",
                 @"A smoke hangs straight on the desert vast,",
                 @"A sun sits round on the endless stream.",
                 @"A horseman bows by a fortress passed:",
                 @"The general’s at the north extreme!"];
self.voiceArray = @[[AVSpeechSynthesisVoice voiceWithLanguage:@"en-GB"],[AVSpeechSynthesisVoice voiceWithLanguage:@"en-US"]];
self.synthesizer = [[AVSpeechSynthesizer alloc]init];
self.isPlay = NO;
[self.controlButton setTitle:@"pause" forState:UIControlStateNormal];
self.synthesizer.delegate = self;
for (int i = 0; i < self.strArray.count;  i ++) {
    AVSpeechUtterance *utterance = [[AVSpeechUtterance alloc]initWithString:self.strArray[i]];
    //需要读的语言
    if (i < 8) {
        utterance.voice = [AVSpeechSynthesisVoice voiceWithLanguage:@"zh-CN"];
    }
    else{
        utterance.voice = self.voiceArray[i%2];
    }
    //语速0.0f~1.0f
    utterance.rate = 0.5f;
    //声音的音调0.5f~2.0f
    utterance.pitchMultiplier = 0.8f;
    //播放下下一句话的时候有多长时间的延迟
    utterance.postUtteranceDelay = 0.1f;
    //上一句之前需要多久
    utterance.preUtteranceDelay = 0.5f;
    //音量
    utterance.volume = 1.0f;
    //开始播放
    [self.synthesizer speakUtterance:utterance];
}
}
//开始朗读的代理方法
- (void)speechSynthesizer:(AVSpeechSynthesizer *)synthesizer didStartSpeechUtterance:(AVSpeechUtterance *)utterance{
NSLog(@"didStartSpeechUtterance->%@",utterance.speechString);
}
//结束朗读的代理方法
- (void)speechSynthesizer:(AVSpeechSynthesizer *)synthesizer didFinishSpeechUtterance:(AVSpeechUtterance *)utterance{
NSLog(@"didFinishSpeechUtterance->%@",utterance.speechString)；    
}
//暂停朗读的代理方法
- (void)speechSynthesizer:(AVSpeechSynthesizer *)synthesizer didPauseSpeechUtterance:(AVSpeechUtterance *)utterance{
NSLog(@"didPauseSpeechUtterance->%@",utterance.speechString);
}
//继续朗读的代理方法
- (void)speechSynthesizer:(AVSpeechSynthesizer *)synthesizer didContinueSpeechUtterance:(AVSpeechUtterance *)utterance{
NSLog(@"didContinueSpeechUtterance->%@",utterance.speechString);
}
//取消朗读的代理方法
- (void)speechSynthesizer:(AVSpeechSynthesizer *)synthesizer didCancelSpeechUtterance:(AVSpeechUtterance *)utterance{
NSLog(@"didCancelSpeechUtterance->%@",utterance.speechString);
}
//将要播放的语音文字
- (void)speechSynthesizer:(AVSpeechSynthesizer *)synthesizer willSpeakRangeOfSpeechString:(NSRange)characterRange utterance:(AVSpeechUtterance *)utterance{
NSLog(@"willSpeakRangeOfSpeechString->characterRange.location = %zd->characterRange.length = %zd->utterance.speechString= %@",characterRange.location,characterRange.length,utterance.speechString);
self.speechLabel.text = utterance.speechString;
}

- (IBAction)buttonClick:(id)sender {
self.isPlay = !self.isPlay;
if (self.isPlay) {
 [self.controlButton setTitle:@"play" forState:UIControlStateNormal];
    [self.synthesizer  pauseSpeakingAtBoundary:AVSpeechBoundaryImmediate];
}
else{
 [self.controlButton setTitle:@"pause" forState:UIControlStateNormal];
    [self.synthesizer continueSpeaking];
}
}

- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}


@end

写在后面：

相关源代码已经上传到网上，里面该有的注释也都有了，感兴趣的同学可以直接上Github下载： AVFoundation相关代码下载地址：点击我就可以了。