录音

在AVFoundation框架中AVAudioRecorder类专门处理录音操作，支持多种音频格式。下面是常用的属性和方法：

属性 说明

@property(readonly, getter=isRecording) BOOL recording; 是否正在录音，只读

@property(readonly) NSURL *url 录音文件地址，只读

@property(readonly) NSDictionary *settings 录音文件设置，只读

@property(readonly) NSTimeInterval currentTime 录音时长，只读，注意仅仅在录音状态可用

@property(readonly) NSTimeInterval deviceCurrentTime 输入设置的时间长度，只读，注意此属性一直可访问

@property(getter=isMeteringEnabled) BOOL meteringEnabled; 是否启用录音测量，如果启用录音测量可以获得录音分贝等数据信息

@property(nonatomic, copy) NSArray *channelAssignments 当前录音的通道

对象方法 说明

- (instancetype)initWithURL:(NSURL )url settings:(NSDictionary )settings error:(NSError **)outError 录音机对象初始化方法，注意其中的url必须是本地文件url，settings是录音格式、编码等设置

- (BOOL)prepareToRecord 准备录音，主要用于创建缓冲区，如果不手动调用，在调用record录音时也会自动调用

- (BOOL)record 开始录音

- (BOOL)recordAtTime:(NSTimeInterval)time 在指定的时间开始录音，一般用于录音暂停再恢复录音

- (BOOL)recordForDuration:(NSTimeInterval) duration 按指定的时长开始录音

- (BOOL)recordAtTime:(NSTimeInterval)time forDuration:(NSTimeInterval) duration 在指定的时间开始录音，并指定录音时长

- (void)pause; 暂停录音

- (void)stop; 停止录音

- (BOOL)deleteRecording; 删除录音，注意要删除录音此时录音机必须处于停止状态

- (void)updateMeters; 更新测量数据，注意只有meteringEnabled为YES此方法才可用

- (float)peakPowerForChannel:(NSUInteger)channelNumber; 指定通道的测量峰值，注意只有调用完updateMeters才有值

- (float)averagePowerForChannel:(NSUInteger)channelNumber 指定通道的测量平均值，注意只有调用完updateMeters才有值

代理方法 说明

- (void)audioRecorderDidFinishRecording:(AVAudioRecorder *)recorder successfully:(BOOL)flag 完成录音

- (void)audioRecorderEncodeErrorDidOccur:(AVAudioRecorder )recorder error:(NSError )error 录音编码发生错误

AVAudioRecorder创建录音机时除了指定路径外还必须指定录音设置信息，因为录音机必须知道录音文件的格式、采样率、通道数、每个采样点的位数等信息，通常只需要几个常用设置。关于录音设置详见帮助文档中的“AV Foundation Audio Settings Constants”。

以下代码实现录音，暂停，继续，取消，停止，播放功能。

#import ViewController.h

#define kAudioFileName @test.caf

@interface ViewController ()

@property (nonatomic,strong) AVAudioRecorder *audioRecorder; //音频录音机
@property (nonatomic,strong) AVAudioPlayer *audioPlayer;     //音频播放器
@property (nonatomic,strong) NSTimer *timer;            //录音监控

@property (weak, nonatomic) IBOutlet UIProgressView *audioPower;

@end

@implementation ViewController

- (void)viewDidLoad {
[super viewDidLoad];
[self setAudioSession];
}

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

/**
*  设置音频会话
*/
-(void)setAudioSession{
AVAudioSession *audioSession=[AVAudioSession sharedInstance];
//设置为播放和录音状态，以便可以在录制完之后播放录音
[audioSession setCategory:AVAudioSessionCategoryPlayAndRecord error:nil];
[audioSession setActive:YES error:nil];
}

/**
*  录音文件设置
*
*  @return 返回录音设置
*/
- (NSDictionary *)getAudioSetting
{
NSMutableDictionary *dic = [NSMutableDictionary dictionary];
[dic setObject:@(kAudioFormatLinearPCM) forKey:AVFormatIDKey];  //设置录音格式
[dic setObject:@(8000) forKey:AVSampleRateKey];                 //设置采样率
[dic setObject:@(1) forKey:AVNumberOfChannelsKey];              //设置通道，这里采用单声道
[dic setObject:@(8) forKey:AVLinearPCMBitDepthKey];             //每个采样点位数，分为8，16，24，32
[dic setObject:@(YES) forKey:AVLinearPCMIsFloatKey];            //是否使用浮点数采样
return dic;
}

/**
*  录音存储路径
*
*  @return 返回存储路径
*/
- (NSURL *)getSavePath
{
NSString *url = [NSSearchPathForDirectoriesInDomains(NSDocumentationDirectory, NSUserDomainMask,YES) lastObject];
url = [url stringByAppendingPathComponent:kAudioFileName];
return [NSURL URLWithString:url];
}

- (NSTimer *)timer
{
if (!_timer) {
_timer = [NSTimer scheduledTimerWithTimeInterval:1 target:self selector:@selector(audioPowerChange) userInfo:nil repeats:YES];
}
return _timer;
}

- (AVAudioRecorder *)audioRecorder
{
if (!_audioRecorder) {
NSError *error = nil;
_audioRecorder = [[AVAudioRecorder alloc] initWithURL:[self getSavePath] settings:[self getAudioSetting] error:&error];
_audioRecorder.delegate = self;
_audioRecorder.meteringEnabled = YES; //是否启用录音测量，如果启用录音测量可以获得录音分贝等数据信息
if (error) {
NSLog(@创建录音机对象发生错误:%@,error.localizedDescription);
return nil;
}
}
return _audioRecorder;
}

- (AVAudioPlayer *)audioPlayer
{
if (!_audioPlayer) {
NSError *error = nil;
_audioPlayer = [[AVAudioPlayer alloc] initWithContentsOfURL:[self getSavePath] error:&error];
if (error) {
NSLog(@创建音频播放器对象发生错误:%@,error.localizedDescription);
return nil;
}
}
return _audioPlayer;
}

#pragma mark -
#pragma mark - AVAudioRecorderDelegate
//录音成功
- (void)audioRecorderDidFinishRecording:(AVAudioRecorder *)recorder successfully:(BOOL)flag
{
if (![self.audioPlayer isPlaying]) {
[self.audioPlayer play];
}
}
//录音失败
- (void)audioRecorderEncodeErrorDidOccur:(AVAudioRecorder *)recorder error:(NSError *)error
{

}

#pragma mark -
#pragma mark - Action

- (void)audioPowerChange{
[self.audioRecorder updateMeters];  //更新测量值
float power = [self.audioRecorder averagePowerForChannel:1]; //取得第一个通道的音频，注意音频强度范围时-160到0
self.audioPower.progress = (1.0/160)*(power+<
4000
span class="hljs-number">160);
}

/**
*  点击录音按钮
*
*  @param sender 录音按钮
*/
- (IBAction)startRecord:(id)sender {

if (![self.audioRecorder isRecording]) {
[self.audioRecorder record];
self.timer.fireDate = [NSDate distantPast];
}
}

/**
*  点击取消录音按钮
*
*  @param sender 取消录音按钮
*/
- (IBAction)cancelRecord:(id)sender {
self.audioRecorder.delegate = nil;
if ([self.audioRecorder isRecording]) {
[self.audioRecorder stop];
}
self.audioRecorder = nil;
}

/**
*  点击暂定按钮
*
*  @param sender 暂停按钮
*/
- (IBAction)pause:(id)sender {
if ([self.audioRecorder isRecording]) {
[self.audioRecorder pause];
self.timer.fireDate = [NSDate distantFuture];
}
}

/**
*  点击恢复按钮
*  恢复录音只需要再次调用record，AVAudioSession会帮助你记录上次录音位置并追加录音
*
*  @param sender 恢复按钮
*/
- (IBAction)goon:(id)sender {
[self startRecord:nil];
}

/**
*  点击停止按钮
*
*  @param sender 停止按钮
*/
- (IBAction)stop:(id)sender {
if ([self.audioRecorder isRecording]) {
[self.audioRecorder stop];
self.timer = [NSDate distantFuture];
}
}

/**
*  点击播放按钮
*
*  @param sender 播放按钮
*/
- (IBAction)play:(id)sender {

if (![self.audioPlayer isPlaying]) {
[self.audioPlayer play];
}
}