iOS 开发将录音文件转换成MP3文件后生成base64传给后端或者回调给前端

#import <Foundation/Foundation.h>

NS_ASSUME_NONNULL_BEGIN


typedef void (^AudioUtilsCallbackBlock)(id responseData);
typedef void (^BackBlock)(BOOL isCanRecord);

@interface WYGreetingCardRecording : NSObject

/**
 开始录音
 */
- (void)startStreamRecord:(AudioUtilsCallbackBlock)block;

/**
结束录音
 */
- (void)stopStreamRecord:(AudioUtilsCallbackBlock)block;


@end

NS_ASSUME_NONNULL_END

.M文件
#import "WYGreetingCardRecording.h"
#import <AVFoundation/AVFoundation.h>
#import "lame.h" //把lame库导入到文件内

@interface WYGreetingCardRecording()<AVAudioRecorderDelegate,AVAudioPlayerDelegate> {
    AVAudioPlayer * player;// 音频播放
    NSURL *recordUrl;
    NSURL *mp3FilePath;
    AVAudioRecorder *audioRecorder;
    AVAudioSession *audioSession;
    NSString *base64Str;
}
@property(nonatomic,copy)AudioUtilsCallbackBlock block;
@end

@implementation WYGreetingCardRecording

//开始录音
- (void)startRecord {
    //开始录音
    //录音设置
    NSMutableDictionary *recordSetting = [[NSMutableDictionary alloc] init];
    //设置录音格式 AVFormatIDKey==kAudioFormatLinearPCM
    [recordSetting setValue:[NSNumber numberWithInt:kAudioFormatLinearPCM] forKey:AVFormatIDKey]; //设置录音采样率(Hz) 如:AVSampleRateKey==8000/44100/96000(影响音频的质量), 采样率必须要设为11025才能使转化 成mp3格式后不会失真
    [recordSetting setValue:[NSNumber numberWithFloat:11025.0] forKey:AVSampleRateKey];
    //录音通道数 1 或 2 ，要转换成mp3格式必须为双通道
    [recordSetting setValue:[NSNumber numberWithInt:2] forKey:AVNumberOfChannelsKey];
    //线性采样位数 8、16、24、32
    [recordSetting setValue:[NSNumber numberWithInt:16] forKey:AVLinearPCMBitDepthKey];
    //录音的质量
    [recordSetting setValue:[NSNumber numberWithInt:AVAudioQualityHigh] forKey:AVEncoderAudioQualityKey];
    //存储录音文件
    recordUrl = [NSURL URLWithString:[NSTemporaryDirectory() stringByAppendingString:@"selfRecord.wav"]];
    //初始化
    audioRecorder = [[AVAudioRecorder alloc] initWithURL:recordUrl settings:recordSetting error:nil]; //开启音量检测
    audioRecorder.meteringEnabled = YES;
    audioSession = [AVAudioSession sharedInstance];//得到AVAudioSession单例对象
    if (![audioRecorder isRecording]) {
        [audioSession setCategory:AVAudioSessionCategoryPlayAndRecord error:nil];//设置类别,表示该应用同时支持播放和录音 [audioSession setActive:YES error:nil];//启动音频会话管理,此时会阻断后台音乐的播放.
        [audioRecorder prepareToRecord];
        [audioRecorder peakPowerForChannel:0.0];
        [audioRecorder record];
        self.block(@{@"code":@"1",@"msg":@"开始录音"});
    }
}

//录音停止
- (void)endRecord {
    
    [audioRecorder stop]; //录音停止
    [audioSession setActive:NO error:nil]; //一定要在录音停止以后再关闭音频会话管理(否则会报错)，此时会延续后台音乐播 放
}

//转成MP3文件
- (void)transformCAFToMP3 {
    mp3FilePath = [NSURL URLWithString:[NSTemporaryDirectory() stringByAppendingString:@"myselfRecord.mp3"]];
    @try {
        int read, write;
        FILE *pcm = fopen([[recordUrl absoluteString] cStringUsingEncoding:1], "rb"); //source 被转换的音频文件位置 fseek(pcm, 4*1024, SEEK_CUR); //skip file header
        if (pcm) {
        FILE *mp3 = fopen([[mp3FilePath absoluteString] cStringUsingEncoding:1], "wb"); //output 输出生成的Mp3文件位置
        const int PCM_SIZE = 8192;
        const int MP3_SIZE = 8192;
        short int pcm_buffer[PCM_SIZE*2];
        unsigned char mp3_buffer[MP3_SIZE];
        lame_t lame = lame_init();
        lame_set_in_samplerate(lame, 11025.0);
        lame_set_VBR(lame, vbr_default);
        lame_init_params(lame);
        do {
            read = (int)fread(pcm_buffer, 2*sizeof(short int), PCM_SIZE, pcm);
            if (read == 0)
                write = lame_encode_flush(lame, mp3_buffer, MP3_SIZE);
            else
                write = lame_encode_buffer_interleaved(lame, pcm_buffer, read, mp3_buffer, MP3_SIZE);
                fwrite(mp3_buffer, write, 1, mp3);
        } while (read != 0);
                lame_close(lame); fclose(mp3); fclose(pcm);
        }
    }@catch (NSException *exception) {
        NSLog(@"%@",[exception description]);
    }@finally {
        NSLog(@"MP3生成成功");
        base64Str = [self mp3ToBASE64];
        NSDictionary *theMessage = [NSDictionary dictionaryWithObjectsAndKeys:@"1",@"code",nullSafe(base64Str),@"base64", nil];
//        NSString *jsonStr = [theMessage mj_JSONString];
        if (self.block) {
            self.block(theMessage);
        }
        
        if(base64Str.length > ) {
            [self deleRecordingFile];
        }
    }
}

//MP3转BASE64
- (NSString *)mp3ToBASE64{
    NSData *mp3Data = [NSData dataWithContentsOfFile:[NSTemporaryDirectory() stringByAppendingString:@"myselfRecord.mp3"]];
    NSString *_encodedImageStr = [mp3Data base64EncodedStringWithOptions:0];
    NSLog(@"===Encoded image:\n%@", _encodedImageStr);
    return _encodedImageStr;
}

//开始录音
- (void)startStreamRecord:(AudioUtilsCallbackBlock)block {
    self.block = block;
    //判断权限
    [self checkPermission:^(BOOL isCan) {
        if (isCan) {
            [self startRecord];
        } else {
            self.block(@{@"code":@"0",@"msg":@"麦克风权限未开启"});
//            [InstanceTool permissionToRemindWithRemindTitle:@"请在iphone的“设置－隐私－麦克风”选项中,允许访问你的麦克风" remindType:IAPermissionToRemindTypeAudio];
        }
    }];
}

//结束录音
- (void)stopStreamRecord:(AudioUtilsCallbackBlock)block {
    self.block = block;
    [self endRecord];
    [self transformCAFToMP3];
}

//麦克风权限请求：
- (BOOL)checkPermission:(BackBlock)block{
  
    __block BOOL bCanRecord = YES;
    if ([[[UIDevice currentDevice]systemVersion]floatValue] >= 7.0) {
        AVAuthorizationStatus videoAuthStatus = [AVCaptureDevice authorizationStatusForMediaType:AVMediaTypeAudio];
         if (videoAuthStatus == AVAuthorizationStatusNotDetermined) {// 未询问用户是否授权
             AVAudioSession *audioSession = [AVAudioSession sharedInstance];
             if ([audioSession respondsToSelector:@selector(requestRecordPermission:)]) {
                 [audioSession performSelector:@selector(requestRecordPermission:) withObject:^(BOOL granted) {
                     if (granted) {
                         bCanRecord = YES;
                     } else {
                         bCanRecord = NO;
                     }
                     block(bCanRecord);
                 }];
             }
         } else if(videoAuthStatus == AVAuthorizationStatusRestricted || videoAuthStatus == AVAuthorizationStatusDenied) {
             NSLog(@"未授权");
             block(NO);
        } else{
            block(YES);
        }
    }
    return bCanRecord;
}

- (void)deleRecordingFile {
    //删除上次生成的文件，保留最新文件
    NSFileManager *fileManager = [NSFileManager defaultManager];
    if ([NSTemporaryDirectory() stringByAppendingString:@"myselfRecord.mp3"]) {
        [fileManager removeItemAtPath:[NSTemporaryDirectory() stringByAppendingString:@"myselfRecord.mp3"] error:nil];
    }
    if ([NSTemporaryDirectory() stringByAppendingString:@"selfRecord.wav"]) {
        [fileManager removeItemAtPath:[NSTemporaryDirectory() stringByAppendingString:@"selfRecord.wav"] error:nil];
    }
}

@end


帖子的录入文字太长了，下一篇专门讲解代码里的宏和引入的文件怎么生成