iOS播放MP3音频

1.新建single view工程，导入AVFoundation库

2.ViewController.xib如图

3.ViewController.h文件

 #import <UIKit/UIKit.h>
 #import <AVFoundation/AVFoundation.h>

 @interface ViewController : UIViewController {
     //进度
     IBOutlet UISlider *_proSlider;
     //声道
     IBOutlet UISlider *_panSlider;
     //速度
     IBOutlet UISlider *_speedSlider;
     //音量
     IBOutlet UISlider *_volSlider;
     IBOutlet UIProgressView *_proV;
     IBOutlet UIProgressView *_proV2;

     AVAudioPlayer *_player;

     NSTimer *_timer;
 }

 - (IBAction)proSlider:(id)sender;
 - (IBAction)panSlider:(id)sender;
 - (IBAction)speedSlider:(id)sender;
 - (IBAction)volSlider:(id)sender;

 - (IBAction)play:(id)sender;
 - (IBAction)pause:(id)sender;

 @end

4.ViewController.m文件

 #import "ViewController.h"

 @implementation ViewController

 - (void)viewDidLoad
 {
     [super viewDidLoad];

     NSString *path = [[NSBundle mainBundle] pathForResource:@"Beat It" ofType:@"mp3"];
 //    NSURL *url = [NSURL URLWithString:path];//不能这样写，因为是本地路径
     NSURL *url = [NSURL fileURLWithPath:path];//本地路径应该这样写

     _player = [[AVAudioPlayer alloc] initWithContentsOfURL:url error:nil];
     //触发play事件的时候会将mp3文件加载到内存中，然后再播放，所以开始的时候可能按按钮的时候会卡，所以需要prepare
     [_player prepareToPlay];
     //设置支持变速
     _player.enableRate = YES;
     //峰值和平均值
     _player.meteringEnabled = YES;

 }

 - (void)play:(id)sender
 {
     //按播放，开始定时器
     _timer = [NSTimer scheduledTimerWithTimeInterval:0.1 target:self selector:@selector(refresh) userInfo:nil repeats:YES];
     [_player play];
 }

 - (void)pause:(id)sender
 {
     [_player pause];
     //定时器失效
     [_timer invalidate];
 }

 - (void)refresh
 {
     //每隔0.1秒刷新一次进度,当前时间/总时间
     float pro = _player.currentTime/_player.duration;
     [_proSlider setValue:pro animated:YES];

     //averagePowerForChannel和peakPowerForChannel的属性分别为声音的最高振幅和平均振幅
     [_player updateMeters];//不刷新就永远是0
     float pead = ([_player peakPowerForChannel:0]+50)/50;//0左声道,1右声道
     float ave = ([_player averagePowerForChannel:0]+50)/50;//同上
     [_proV setProgress:pead animated:YES];
     [_proV2 setProgress:ave animated:YES];
 }

 //进度
 - (IBAction)proSlider:(id)sender
 {
     //当前时间=总时间*slider.value;
     float curTime = _player.duration*_proSlider.value;
     [_player setCurrentTime:curTime];
 }
 //声道
 - (IBAction)panSlider:(id)sender
 {
     _player.pan = _panSlider.value;
 }
 //速度
 - (IBAction)speedSlider:(id)sender
 {
     _player.rate = _speedSlider.value;
 }
 //音量
 - (IBAction)volSlider:(id)sender
 {
     _player.volume = _volSlider.value;
 }

 @end