OCiOS开发：音频播放器 AVAudioPlayer

简单介绍

• AVAudioPlayer音频播放器可以提供简单的音频播放功能。其头文件包括在AVFoudation.framework中。
• AVAudioPlayer未提供可视化界面，须要通过其提供的播放控制接口自行实现。
• AVAudioPlayer仅能播放本地音频文件，并支持以下格式文件：.mp3、.m4a、.wav、.caf、.aif?。

经常用法

• 初始化方法

// 1、NSURL 它仅仅能从file://格式的URL装入音频数据，不支持流式音频及HTTP流和网络流。

- (id)initWithContentsOfURL:(NSURL *)url error:(NSError **)outError;

// 2、它使用一个指向内存中一些音频数据的NSData对象，这样的形式对于已经把音频数据下载到缓冲区的情形非常实用。
- (id)initWithData:(NSData *)data error:(NSError **)outError;

• 音频操作方法

1、将音频资源加入音频队列，准备播放
- (BOOL)prepareToPlay;

2、開始播放音乐
- (BOOL)play;

3、在指定的延迟时间后開始播放
- (BOOL)playAtTime:(NSTimeInterval)time

4、暂停播放
- (void)pause;

5、停止播放
- (void)stop;           

经常使用属性

• playing：查看播放器是否处于播放状态
• duration：获取音频播放总时长
• delegate：设置托付
• currentTime：设置播放当前时间
• numberOfLoops：设置播放循环
• pan：设置声道
• rate：设置播放速度

AVAudioPlayerDelegate

• AVAudioPlayerDelegate托付协议包括了大量的播放状态协议方法，来对播放的不同状态事件进行自己定义处理：

// 1、完毕播放
- (void)audioPlayerDidFinishPlaying:(AVAudioPlayer *)player successfully:(BOOL)flag;

// 2、播放失败
- (void)audioPlayerDecodeErrorDidOccur:(AVAudioPlayer *)player error:(NSError *)error;

// 3、音频中断

// 播放中断结束后，比方突然来的电话造成的中断
- (void)audioPlayerEndInterruption:(AVAudioPlayer *)player withOptions:(NSUInteger)flags;

- (void)audioPlayerBeginInterruption:(AVAudioPlayer *)player;

- (void)audioPlayerEndInterruption:(AVAudioPlayer *)player withFlags:(NSUInteger)flags;

- (void)audioPlayerEndInterruption:(AVAudioPlayer *)player;

AVURLAsset获取专辑信息

通过AVURLAsset可获取mp3专辑信息，包括专辑名称、专辑图片、歌曲名、艺术家、专辑缩略图等信息。

commonKey

• AVMetadataCommonKeyArtist：艺术家
• AVMetadataCommonKeyTitle：音乐名
• AVMetadataCommonKeyArtwork：专辑图片
• AVMetadataCommonKeyAlbumName：专辑名称

获取步骤

steps 1：初始化

// 获取音频文件路径集合（获取全部的.mp3格式的文件路径）
   NSArray *musicNames = [NSArray arrayWithArray:[[NSBundle mainBundle] pathsForResourcesOfType:@"mp3" inDirectory:nil]];

// 获取最后一首歌曲（假定获取最后一首歌曲）的专辑信息
   NSString *musicName = [musicNames.lastObject lastPathComponent];

// 依据歌曲名称获取音频路径
   NSString *path = [[NSBundle mainBundle] pathForAuxiliaryExecutable:musicName];

// 依据音频路径创建资源地址
   NSURL *url = [NSURL fileURLWithPath:path];

// 初始化AVURLAsset
   AVURLAsset *mp3Asset = [AVURLAsset URLAssetWithURL:url];

steps 2：遍历获取信息

// 遍历有效元数据格式
    for (NSString *format in [mp3Asset availableMetadataFormats]) {

        // 依据数据格式获取AVMetadataItem（数据成员）。
        // 依据AVMetadataItem属性commonKey可以获取专辑信息；
        for (AVMetadataItem *metadataItem in [mp3Asset metadataForFormat:format]) {
            // NSLog(@"%@", metadataItem);

            // 1、获取艺术家（歌手）名字commonKey：AVMetadataCommonKeyArtist
            if ([metadataItem.commonKey isEqual:AVMetadataCommonKeyArtist]) {
                NSLog(@"%@", (NSString *)metadataItem.value);
            }
            // 2、获取音乐名字commonKey：AVMetadataCommonKeyTitle
            else if ([metadataItem.commonKey isEqual:AVMetadataCommonKeyTitle]) {
                NSLog(@"%@", (NSString *)metadataItem.value);
            }
            // 3、获取专辑图片commonKey：AVMetadataCommonKeyArtwork
            else if ([metadataItem.commonKey isEqual:AVMetadataCommonKeyArtwork]) {
                NSLog(@"%@", (NSData *)metadataItem.value);
            }
            // 4、获取专辑名commonKey：AVMetadataCommonKeyAlbumName
            else if ([metadataItem.commonKey isEqual:AVMetadataCommonKeyAlbumName]) {
                NSLog(@"%@", (NSString *)metadataItem.value);
            }
        }
    }

音频播放器案例

案例主要实现：播放、暂停、上一曲、下一曲、拖动滑条改变音量、拖动滑条改变当前进度、播放当前时间以及剩余时间显示、通过AVURLAsset类获取音频的专辑信息（包括专辑图片、歌手、歌曲名等）。

素材下载

下载地址：http://download.csdn.net/download/hierarch_lee/9415973

效果展示

代码演示样例

上述展示效果中，歌曲名称实际上是导航栏标题。我仅仅是将导航栏背景颜色设置成黑色。标题颜色以及状态栏颜色设置成白色。

加入导航栏、导航栏配置以及改动状态栏颜色。这里省略，以下直接贴上实现代码。

#import <UIKit/UIKit.h>

@interface ViewController : UIViewController

@end

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

typedef enum : NSUInteger {
    PlayAndPauseBtnTag,
    NextMusicBtnTag,
    LastMusicBtnTag,
} BtnTag;

#define TIME_MINUTES_KEY @"minutes" // 时间_分_键
#define TIME_SECONDS_KEY @"seconds" // 时间_秒_键

#define RGB_COLOR(_R,_G,_B) [UIColor colorWithRed:_R/255.0 green:_G/255.0 blue:_B/255.0 alpha:1]

@interface ViewController () <AVAudioPlayerDelegate>

{
    NSTimer *_timer; /**< 定时器 */

    BOOL _playing; /**< 播放状态 */
    BOOL _shouldUpdateProgress; /**< 是否更新进度指示器 */

    NSArray *_musicNames; /**< 音乐名集合 */

    NSInteger _currentMusicPlayIndex; /**< 当前音乐播放下标 */
}

@property (nonatomic, strong) UILabel     *singerLabel;/**< 歌手 */
@property (nonatomic, strong) UIImageView *imageView;/**< 专辑图片 */
@property (nonatomic, strong) UIImageView *volumeImageView; /**< 音量图片 */

@property (nonatomic, strong) UISlider *slider;/**< 进度指示器 */
@property (nonatomic, strong) UISlider *volumeSlider;/**< 音量滑条 */

@property (nonatomic, strong) UIButton *playAndPauseBtn; /**< 暂停播放button */
@property (nonatomic, strong) UIButton *nextMusicBtn; /**< 下一曲button */
@property (nonatomic, strong) UIButton *lastMusicBtn; /**< 上一曲button */

@property (nonatomic, strong) UILabel *currentTimeLabel; /**< 当前时间 */
@property (nonatomic, strong) UILabel *remainTimeLabel;  /**< 剩余时间 */

@property (nonatomic, strong) AVAudioPlayer *audioPlayer; /**< 音频播放器 */

// 初始化
- (void)initializeDataSource; /**< 初始化数据源 */
- (void)initializeUserInterface; /**< 初始化用户界面 */
- (void)initializeAudioPlayerWithMusicName:(NSString *)musicName shouleAutoPlay:(BOOL)autoPlay; /**< 初始化音频播放器 */

// 更新
- (void)updateSlider; /**< 刷新滑条 */
- (void)updateUserInterface; /**< 刷新用户界面 */
- (void)updateTimeDisplayWithDuration:(NSTimeInterval)duration currentTime:(NSTimeInterval)currentTime; /**< 更新时间显示 */

// 定时器
- (void)startTimer; /**< 启动定时器 */
- (void)pauseTimer; /**< 暂停定时器 */
- (void)stopTimer;  /**< 停止定时器 */

// 事件方法
- (void)respondsToButton:(UIButton *)sender; /**< 点击button */

- (void)respondsToSliderEventValueChanged:(UISlider *)sender; /**< 拖动滑条 */
- (void)respondsToSliderEventTouchDown:(UISlider *)sender; /**< 按下滑条 */
- (void)respondsToSliderEventTouchUpInside:(UISlider *)sender; /**< 滑条按下抬起 */
- (void)respondsToVolumeSlider:(UISlider *)sender; /**< 拖动音量滑条 */

// 其它方法
- (NSDictionary *)handleWithTime:(NSTimeInterval)time; /**< 处理时间 */

@end

@implementation ViewController

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

#pragma mark *** Initialize methods ***
- (void)initializeDataSource {

    // 赋值是否播放。初始化音频播放器时。不播放音乐
    _playing = NO;

    // 赋值是否刷新进度指示
    _shouldUpdateProgress = YES;

    // 设置当前播放音乐下标
    _currentMusicPlayIndex = 0;

    // 获取bundle路径全部的mp3格式文件集合
    _musicNames = [NSArray arrayWithArray:[[NSBundle mainBundle] pathsForResourcesOfType:@"mp3" inDirectory:nil]];

    [_musicNames enumerateObjectsUsingBlock:^(NSString *  _Nonnull musicName, NSUInteger idx, BOOL * _Nonnull stop) {
        NSLog(@"%@", musicName.lastPathComponent);
    }];

}

- (void)initializeUserInterface {

    self.view.backgroundColor = [UIColor blackColor];
    self.navigationController.navigationBar.barTintColor = [UIColor blackColor];
    self.navigationController.navigationBar.tintColor = [UIColor whiteColor];
    self.navigationController.navigationBar.titleTextAttributes = @{NSFontAttributeName:[UIFont boldSystemFontOfSize:25],
                                                                    NSForegroundColorAttributeName:[UIColor whiteColor]};

    // 载入视图
    [self.view addSubview:self.singerLabel];
    [self.view addSubview:self.imageView];
    [self.view addSubview:self.slider];

    [self.view addSubview:self.playAndPauseBtn];
    [self.view addSubview:self.nextMusicBtn];
    [self.view addSubview:self.lastMusicBtn];

    [self.view addSubview:self.currentTimeLabel];
    [self.view addSubview:self.remainTimeLabel];

    [self.view addSubview:self.volumeSlider];
    [self.view addSubview:self.volumeImageView];

    // 初始化音乐播放器
    [self initializeAudioPlayerWithMusicName:_musicNames[_currentMusicPlayIndex] shouleAutoPlay:_playing];
}

- (void)initializeAudioPlayerWithMusicName:(NSString *)musicName shouleAutoPlay:(BOOL)autoPlay {
    // 异常处理
    if (musicName.length == 0) {
        return;
    }

    NSError *error = nil;

    // 获取音频地址
    NSURL *url = [[NSBundle mainBundle] URLForAuxiliaryExecutable:musicName];

    // 初始化音频播放器
    self.audioPlayer = [[AVAudioPlayer alloc] initWithContentsOfURL:url error:&error];

    // 设置代理
    self.audioPlayer.delegate = self;

    // 推断是否异常
    if (error) {
        // 打印异常描写叙述信息
        NSLog(@"%@", error.localizedDescription);
    }else {

        // 设置音量
        self.audioPlayer.volume = self.volumeSlider.value;

        // 准备播放
        [self.audioPlayer prepareToPlay];

        // 播放持续时间
        NSLog(@"音乐持续时间：%.2f", self.audioPlayer.duration);

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

    // 更新用户界面
    [self updateUserInterface];
}

#pragma mark *** Timer ***
- (void)startTimer {
    if (!_timer) {
        _timer = [NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:@selector(updateSlider) userInfo:nil repeats:YES];
    }
    _timer.fireDate = [NSDate date];
}

- (void)pauseTimer {
    _timer.fireDate = [NSDate distantFuture];
}

- (void)stopTimer {
    // 销毁定时器
    if ([_timer isValid]) {
        [_timer invalidate];
    }
}

#pragma mark *** Events ***
- (void)respondsToButton:(UIButton *)sender {
    switch (sender.tag) {
            // 暂停播放
        case PlayAndPauseBtnTag: {
            if (!_playing) {
                [_audioPlayer play];
                [self startTimer];
            }else {
                [_audioPlayer pause];
                [self pauseTimer];
            }
            _playing = !_playing;
            sender.selected = _playing;
        }
            break;
            // 上一曲
        case LastMusicBtnTag: {
            _currentMusicPlayIndex = _currentMusicPlayIndex == 0 ?

_musicNames.count - 1 : --_currentMusicPlayIndex;
            [self initializeAudioPlayerWithMusicName:[_musicNames[_currentMusicPlayIndex] lastPathComponent] shouleAutoPlay:_playing];
        }
            break;
            // 下一曲
        case NextMusicBtnTag: {
            _currentMusicPlayIndex = _currentMusicPlayIndex == _musicNames.count - 1 ? 0 : ++_currentMusicPlayIndex;
            [self initializeAudioPlayerWithMusicName:[_musicNames[_currentMusicPlayIndex] lastPathComponent] shouleAutoPlay:_playing];
        }
            break;

        default:
            break;
    }
}

// 拖动滑条更新时间显示
- (void)respondsToSliderEventValueChanged:(UISlider *)sender {
    [self updateTimeDisplayWithDuration:sender.maximumValue currentTime:sender.value];
}

// 滑条按下时停止更新滑条
- (void)respondsToSliderEventTouchDown:(UISlider *)sender {
    _shouldUpdateProgress = NO;
}

// 滑条按下抬起，更新当前音乐播放时间
- (void)respondsToSliderEventTouchUpInside:(UISlider *)sender {
    _shouldUpdateProgress = YES;
    self.audioPlayer.currentTime = sender.value;
}

- (void)respondsToVolumeSlider:(UISlider *)sender {
    self.audioPlayer.volume = sender.value;
}

#pragma mark *** Update methods ***
- (void)updateSlider {
    // 在拖动滑条的过程中，停止刷新播放进度
    if (_shouldUpdateProgress) {
        // 更新进度指示
        self.slider.value = self.audioPlayer.currentTime;
        // 更新时间显示
        [self updateTimeDisplayWithDuration:self.audioPlayer.duration currentTime:self.audioPlayer.currentTime];
    }
}

- (void)updateUserInterface {

    /* 进度指示更新 */
    self.slider.value = 0.0;
    self.slider.minimumValue = 0.0;
    self.slider.maximumValue = self.audioPlayer.duration;

    /* 标题更新 */
    self.title = [_musicNames[_currentMusicPlayIndex] substringToIndex:((NSString *)_musicNames[_currentMusicPlayIndex]).length - 4];

    /* 获取MP3专辑信息 */
    // 获取音乐路径
    NSString *path = [[NSBundle mainBundle] pathForAuxiliaryExecutable:[_musicNames[_currentMusicPlayIndex] lastPathComponent]];
    // 依据音乐路径创建url资源地址
    NSURL *url = [NSURL fileURLWithPath:path];
    // 初始化AVURLAsset
    AVURLAsset *map3Asset = [AVURLAsset assetWithURL:url];
    // 遍历有效元数据格式
    for (NSString *format in [map3Asset availableMetadataFormats]) {
        // 依据数据格式获取AVMetadataItem数据成员
        for (AVMetadataItem *metadataItem in [map3Asset metadataForFormat:format]) {
            // 获取专辑图片commonKey：AVMetadataCommonKeyArtwork
            if ([metadataItem.commonKey isEqualToString:AVMetadataCommonKeyArtwork]) {
                UIImage *image = [UIImage imageWithData:(NSData *)metadataItem.value];
                // 更新专辑图片
                self.imageView.image = image;
            }
            // 获取音乐名字commonKey：AVMetadataCommonKeyTitle
            else if([metadataItem.commonKey isEqualToString:AVMetadataCommonKeyTitle]){
                // 更新音乐名称
                self.title = (NSString *)metadataItem.value;
            }
            // 获取艺术家（歌手）名字commonKey：AVMetadataCommonKeyArtist
            else if ([metadataItem.commonKey isEqual:AVMetadataCommonKeyArtist]){
                // 更新歌手
                self.singerLabel.text = [NSString stringWithFormat:@"- %@ -", metadataItem.value];
            }
        }
    }
}

- (void)updateTimeDisplayWithDuration:(NSTimeInterval)duration currentTime:(NSTimeInterval)currentTime {
    /* 处理当前时间 */
    NSDictionary *currentTimeInfoDict = [self handleWithTime:currentTime];
    // 取出相应的分秒组件
    NSInteger currentMinutes = [[currentTimeInfoDict objectForKey:TIME_MINUTES_KEY] integerValue];
    NSInteger currentSeconds = [[currentTimeInfoDict objectForKey:TIME_SECONDS_KEY] integerValue];
    // 时间格式处理
    NSString *currentTimeFormat = currentSeconds < 10 ? @"0%d:0%d" : @"0%d:%d";
    NSString *currentTimeString = [NSString stringWithFormat:currentTimeFormat, currentMinutes, currentSeconds];
    self.currentTimeLabel.text = currentTimeString;

    /* 处理剩余时间 */
    NSDictionary *remainTimeInfoDict = [self handleWithTime:duration - currentTime];
    // 取出相应的过分秒组件
    NSInteger remainMinutes = [[remainTimeInfoDict objectForKey:TIME_MINUTES_KEY] integerValue];
    NSInteger remainSeconds = [[remainTimeInfoDict objectForKey:TIME_SECONDS_KEY] integerValue];
    // 时间格式处理
    NSString *remainTimeFormat = remainSeconds < 10 ? @"0%d:0%d" : @"-0%d:%d";
    NSString *remainTimeString = [NSString stringWithFormat:remainTimeFormat, remainMinutes, remainSeconds];
    self.remainTimeLabel.text = remainTimeString;
}

- (NSDictionary *)handleWithTime:(NSTimeInterval)time {
    NSMutableDictionary *timeInfomationDict = [@{} mutableCopy];
    // 获取分
    NSInteger minutes = (NSInteger)time/60;
    // 获取秒
    NSInteger seconds = (NSInteger)time%60;
    // 打包字典
    [timeInfomationDict setObject:@(minutes) forKey:TIME_MINUTES_KEY];
    [timeInfomationDict setObject:@(seconds) forKey:TIME_SECONDS_KEY];
    return timeInfomationDict;
}

#pragma mark *** AVAudioPlayerDelegate ***
- (void)audioPlayerDidFinishPlaying:(AVAudioPlayer *)player successfully:(BOOL)flag {
    [self respondsToButton:self.nextMusicBtn];
}

#pragma mark *** Setters ***
- (void)setAudioPlayer:(AVAudioPlayer *)audioPlayer {
    // 在设置音频播放器的时候，假设正在播放，则先暂停音乐再进行配置
    if (_audioPlayer.playing) {
        [_audioPlayer stop];
    }
    _audioPlayer = audioPlayer;
}

#pragma mark *** Getters ***
- (UILabel *)singerLabel {
    if (!_singerLabel) {
        _singerLabel = [[UILabel alloc] init];
        _singerLabel.bounds = CGRectMake(0, 0, CGRectGetWidth(self.view.bounds), 40);
        _singerLabel.center = CGPointMake(CGRectGetMidX(self.view.bounds), 64 + CGRectGetMidY(_singerLabel.bounds));
        _singerLabel.textColor = [UIColor whiteColor];
        _singerLabel.font = [UIFont systemFontOfSize:17];
        _singerLabel.textAlignment = NSTextAlignmentCenter;
    }
    return _singerLabel;
}

- (UIImageView *)imageView {
    if (!_imageView) {
        _imageView = [[UIImageView alloc] init];
        _imageView.bounds = CGRectMake(0, 0, CGRectGetWidth(self.view.bounds) - 180, CGRectGetWidth(self.view.bounds) - 180);
        _imageView.center = CGPointMake(CGRectGetMidX(self.view.bounds), CGRectGetMaxY(self.singerLabel.frame) + CGRectGetMidY(_imageView.bounds) + 30);
        _imageView.backgroundColor = [UIColor cyanColor];
        _imageView.layer.cornerRadius = CGRectGetMidX(_imageView.bounds);
        _imageView.layer.masksToBounds = YES;
        _imageView.alpha = 0.85;
    }
    return _imageView;
}

- (UISlider *)slider {
    if (!_slider) {
        _slider = [[UISlider alloc] init];
        _slider.bounds = CGRectMake(0, 0, CGRectGetWidth(self.view.bounds) - 100, 30);
        _slider.center = CGPointMake(CGRectGetMidX(self.view.bounds), CGRectGetMaxY(self.imageView.frame) + CGRectGetMidY(_slider.bounds) + 50);
        _slider.maximumTrackTintColor = [UIColor lightGrayColor];
        _slider.minimumTrackTintColor = RGB_COLOR(30, 177, 74);
        _slider.layer.masksToBounds = YES;

        // 自己定义拇指图片
        [_slider setThumbImage:[UIImage imageNamed:@"iconfont-yuan"] forState:UIControlStateNormal];

        // 事件监听
        [_slider addTarget:self action:@selector(respondsToSliderEventValueChanged:) forControlEvents:UIControlEventValueChanged];
        [_slider addTarget:self action:@selector(respondsToSliderEventTouchDown:) forControlEvents:UIControlEventTouchDown];
        [_slider addTarget:self action:@selector(respondsToSliderEventTouchUpInside:) forControlEvents:UIControlEventTouchUpInside];

    }
    return _slider;
}

- (UIButton *)playAndPauseBtn {
    if (!_playAndPauseBtn) {
        _playAndPauseBtn = [UIButton buttonWithType:UIButtonTypeCustom];
        _playAndPauseBtn.bounds = CGRectMake(0, 0, 100, 100);
        _playAndPauseBtn.center = CGPointMake(CGRectGetMidX(self.view.bounds), CGRectGetMaxY(self.slider.frame) + CGRectGetMidY(_playAndPauseBtn.bounds) + 30);
        _playAndPauseBtn.tag = PlayAndPauseBtnTag;
        [_playAndPauseBtn setImage:[UIImage imageNamed:@"iconfont-bofang"] forState:UIControlStateNormal];
        [_playAndPauseBtn setImage:[UIImage imageNamed:@"iconfont-zanting"] forState:UIControlStateSelected];
        [_playAndPauseBtn addTarget:self action:@selector(respondsToButton:) forControlEvents:UIControlEventTouchUpInside];
    }
    return _playAndPauseBtn;
}

- (UIButton *)nextMusicBtn {
    if (!_nextMusicBtn) {
        _nextMusicBtn = [UIButton buttonWithType:UIButtonTypeCustom];
        _nextMusicBtn.bounds = CGRectMake(0, 0, 60, 60);
        _nextMusicBtn.center = CGPointMake(CGRectGetMaxX(self.playAndPauseBtn.frame) + CGRectGetMidX(_nextMusicBtn.bounds) + 20, CGRectGetMidY(self.playAndPauseBtn.frame));
        _nextMusicBtn.tag = NextMusicBtnTag;
        [_nextMusicBtn setImage:[UIImage imageNamed:@"iconfont-xiayiqu"] forState:UIControlStateNormal];
        [_nextMusicBtn addTarget:self action:@selector(respondsToButton:) forControlEvents:UIControlEventTouchUpInside];
    }
    return _nextMusicBtn;
}

- (UIButton *)lastMusicBtn {
    if (!_lastMusicBtn) {
        _lastMusicBtn = [UIButton buttonWithType:UIButtonTypeCustom];
        _lastMusicBtn.bounds = CGRectMake(0, 0, 60, 60);
        _lastMusicBtn.center = CGPointMake(CGRectGetMinX(self.playAndPauseBtn.frame) - 20 - CGRectGetMidX(_lastMusicBtn.bounds), CGRectGetMidY(self.playAndPauseBtn.frame));
        _lastMusicBtn.tag = LastMusicBtnTag;
        [_lastMusicBtn setImage:[UIImage imageNamed:@"iconfont-shangyiqu"] forState:UIControlStateNormal];
        [_lastMusicBtn addTarget:self action:@selector(respondsToButton:) forControlEvents:UIControlEventTouchUpInside];
    }
    return _lastMusicBtn;
}

- (UILabel *)currentTimeLabel {
    if (!_currentTimeLabel) {
        _currentTimeLabel = [[UILabel alloc] init];
        _currentTimeLabel.bounds = CGRectMake(0, 0, 50, 30);
        _currentTimeLabel.center = CGPointMake(CGRectGetMidX(_currentTimeLabel.bounds), CGRectGetMidY(self.slider.frame));
        _currentTimeLabel.textAlignment = NSTextAlignmentRight;
        _currentTimeLabel.font = [UIFont systemFontOfSize:14];
        _currentTimeLabel.textColor = [UIColor lightGrayColor];
        _currentTimeLabel.text = @"00:00";
    }
    return _currentTimeLabel;
}

- (UILabel *)remainTimeLabel {
    if (!_remainTimeLabel) {
        _remainTimeLabel = [[UILabel alloc] init];
        _remainTimeLabel.bounds = self.currentTimeLabel.bounds;
        _remainTimeLabel.center = CGPointMake(CGRectGetMaxX(self.slider.frame) + CGRectGetMidX(_remainTimeLabel.bounds), CGRectGetMidY(self.slider.frame));
        _remainTimeLabel.font = [UIFont systemFontOfSize:14];
        _remainTimeLabel.textColor = [UIColor lightGrayColor];
        _remainTimeLabel.text = @"00:00";
    }
    return _remainTimeLabel;
}

- (UIImageView *)volumeImageView {
    if (!_volumeImageView) {
        _volumeImageView = [[UIImageView alloc] init];
        _volumeImageView.bounds = CGRectMake(0, 0, 35, 35);
        _volumeImageView.center = CGPointMake(20 + CGRectGetMidX(_volumeImageView.bounds),  CGRectGetMaxY(self.playAndPauseBtn.frame) + CGRectGetMidY(_volumeImageView.bounds) + 40);
        _volumeImageView.image = [UIImage imageNamed:@"iconfont-yinliang"];
    }
    return _volumeImageView;
}

- (UISlider *)volumeSlider {
    if (!_volumeSlider) {
        _volumeSlider = [[UISlider alloc] init];
        _volumeSlider.bounds = CGRectMake(0, 0, CGRectGetWidth(self.view.bounds) - 2 * CGRectGetMinX(self.volumeImageView.frame) - CGRectGetWidth(self.volumeImageView.bounds), CGRectGetHeight(self.slider.bounds));
        _volumeSlider.center = CGPointMake(CGRectGetMaxX(self.volumeImageView.frame) + CGRectGetMidX(_volumeSlider.bounds), CGRectGetMidY(self.volumeImageView.frame));
        _volumeSlider.maximumTrackTintColor = [UIColor lightGrayColor];
        _volumeSlider.minimumTrackTintColor = RGB_COLOR(30, 177, 74);
        _volumeSlider.minimumValue = 0.0;
        _volumeSlider.maximumValue = 1.0;
        _volumeSlider.value = 0.5;
        [_volumeSlider setThumbImage:[UIImage imageNamed:@"iconfont-yuan"] forState:UIControlStateNormal];
        [_volumeSlider addTarget:self action:@selector(respondsToVolumeSlider:) forControlEvents:UIControlEventValueChanged];
    }
    return _volumeSlider;
}
@end