获取项目中对应txt文件的内容，并且将获得到的文本转成语音播报

#import "ViewController.h"
#import <AVFoundation/AVSpeechSynthesis.h>

@interface ViewController ()<AVSpeechSynthesizerDelegate>

// 播放暂停按钮  xib
@property (weak, nonatomic) IBOutlet UIButton *startBtn;
// 语音合成器
@property (nonatomic, strong) AVSpeechSynthesizer *synthesizer;

@end

@implementation ViewController

- (void)viewDidLoad {
   [super viewDidLoad];
   
   [self.startBtn setTitle:@"开始" forState:0];
   [self.startBtn setTitle:@"暂停" forState:UIControlStateSelected];
   
}

- (NSString *)getTxtFileContent {
   // 获取txt文件中的文本内容
   NSString *filePath = [[NSBundle mainBundle] pathForResource:@"MyTestFile" ofType:@"txt"];
   NSString *text = [NSString stringWithContentsOfFile:filePath encoding:NSUTF8StringEncoding error:nil];
   return text;
}

// 朗读文本内容方法
- (void)readingContentText:(NSString *)text {
   
   if (!self.synthesizer) {
       self.synthesizer = [[AVSpeechSynthesizer alloc] init];
       self.synthesizer.delegate = self;
   }
   
   // 将需要朗读的文本合成语音
   AVSpeechUtterance *utterance = [[AVSpeechUtterance alloc] initWithString:text];
   
   /*
    avspeech支持的语言种类包括：
    "th-TH","pt-BR","sk-SK","fr-CA","ro-RO","no-NO","fi-FI","pl-PL","de-DE",
    "nl-NL","id-ID","tr-TR","it-IT","pt-PT","fr-FR","ru-RU","es-MX","zh-HK",
    中文(香港)粤语"sv-SE","hu-HU","zh-TW",中文(台湾)"es-ES","zh-CN",中文(普通话)
    "nl-BE","en-GB",英语(英国)"ar-SA","ko-KR","cs-CZ","en-ZA","en-AU","da-DK",
    "en-US",英语(美国)"en-IE","hi-IN","el-GR","ja-JP"
    */
   // 这里合成语音的语言 中文
   AVSpeechSynthesisVoice *voicLanguage = [AVSpeechSynthesisVoice voiceWithLanguage:@"zh-CN"];
   utterance.voice = voicLanguage;
   // 语速 0.0f ~ 1.0f
   utterance.rate = 0.5f;
   // 声音的音调 0.5f ~ 2.0f
   utterance.pitchMultiplier = 1.0f;
   // 使播放下一句的时候有0.1秒的延迟
   utterance.postUtteranceDelay = 0.1f;
   // 设置音量大小 0.0f ~ 1.0f
   utterance.volume = 0.1f;
   
   // 播放合成语音
   [self.synthesizer speakUtterance:utterance];
   
   
}


// 开始 暂停按钮事件
- (IBAction)startButtonAction:(UIButton *)button {
   
   if (button.selected) {
       
       // 暂停
       [self.startBtn setTitle:@"开始" forState:0];
       
       // 判断是否播放中，如果播放中则暂停播放
       if ([self.synthesizer isSpeaking]) {
           [self.synthesizer pauseSpeakingAtBoundary:AVSpeechBoundaryWord];
       }
   }
   else {
       
       // 开始
       [self.startBtn setTitle:@"暂停" forState:UIControlStateSelected];
       
       // 判断是否暂停播放
       if ([self.synthesizer isPaused]) {
           [self.synthesizer continueSpeaking];
       }
       else {
           // 如果没有暂停，则重新创建新的播放语音并且开始播放
           NSString *text = [self getTxtFileContent];
           [self readingContentText:text];
       }
   }
   
   button.selected = !button.selected;
   
}

#pragma mark - AVSpeechSynthesizerDelegate

// 开始播放
- (void)speechSynthesizer:(AVSpeechSynthesizer *)synthesizer didStartSpeechUtterance:(AVSpeechUtterance *)utterance {
   NSLog(@"开始播放");
}
- (void)speechSynthesizer:(AVSpeechSynthesizer *)synthesizer didFinishSpeechUtterance:(AVSpeechUtterance *)utterance {
   NSLog(@"完成播放");
   self.startBtn.selected = !self.startBtn.selected;
}
- (void)speechSynthesizer:(AVSpeechSynthesizer *)synthesizer didPauseSpeechUtterance:(AVSpeechUtterance *)utterance {
   NSLog(@"暂停播放");
}
- (void)speechSynthesizer:(AVSpeechSynthesizer *)synthesizer didContinueSpeechUtterance:(AVSpeechUtterance *)utterance {
   NSLog(@"恢复播放");
}
- (void)speechSynthesizer:(AVSpeechSynthesizer *)synthesizer didCancelSpeechUtterance:(AVSpeechUtterance *)utterance {
   NSLog(@"取消播放");
}

- (void)speechSynthesizer:(AVSpeechSynthesizer *)synthesizer willSpeakRangeOfSpeechString:(NSRange)characterRange utterance:(AVSpeechUtterance *)utterance {
   NSLog(@"将要播放某一段语音");
}