iOS播放MP3音頻

1.建立single view工程，導入AVFoundation庫

2.ViewController.xib如圖

3.ViewController.h檔案

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

@interface ViewController : UIViewController {
    //進度
    IBOutlet UISlider *_proSlider;
    //聲道
    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檔案

#import "ViewController.h"

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
	
    NSString *path = [[NSBundle mainBundle] pathForResource:@"Beat It" ofType:@"mp3"];
//    NSURL *url = [NSURL URLWithString:path];//不能這樣寫，因為是本地路徑
    NSURL *url = [NSURL fileURLWithPath:path];//本地路徑應該這樣寫
    
    _player = [[AVAudioPlayer alloc] initWithContentsOfURL:url error:nil];
    //觸發play事件的時候會将mp3檔案加載到記憶體中，然後再播放，是以開始的時候可能按按鈕的時候會卡，是以需要prepare
    [_player prepareToPlay];
    //設定支援變速
    _player.enableRate = YES;
    //峰值和平均值
    _player.meteringEnabled = YES;

}

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

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

- (void)refresh
{
    //每隔0.1秒重新整理一次進度,目前時間/總時間
    float pro = _player.currentTime/_player.duration;
    [_proSlider setValue:pro animated:YES];
    
    //averagePowerForChannel和peakPowerForChannel的屬性分别為聲音的最高振幅和平均振幅
    [_player updateMeters];//不重新整理就永遠是0
    float pead = ([_player peakPowerForChannel:0]+50)/50;//0左聲道,1右聲道
    float ave = ([_player averagePowerForChannel:0]+50)/50;//同上
    [_proV setProgress:pead animated:YES];
    [_proV2 setProgress:ave animated:YES];
}

//進度
- (IBAction)proSlider:(id)sender
{
    //目前時間=總時間*slider.value;
    float curTime = _player.duration*_proSlider.value;
    [_player setCurrentTime:curTime];
}
//聲道
- (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