AVAudioPlayer音頻播放

AVAudioPlayer類創建的實例可以看作為一個音頻播放器，可以播放來自文件或存儲的音頻數據。
它支持多種音頻格式，而且能夠進行進度、音量、播放速度等控制。
使用這個類，可以：
1、在指定的時間開始播放音頻
2、從文件或內存緩沖區播放音頻
3、循環播放

 

屬性	描述
@property(readonly, getter=isPlaying) BOOL playing	是否正在播放，只讀
@property float volume	音量大小，范圍0~1.0
@property float pan	立體聲，-1.0完全左聲道，0.0左右聲道平衡，1.0完全右聲道
@property float rate	播放速率，范圍0.5～2.0，1.0時為正常播放，如果需要更改播放速率必須設置enableRate為YES
@property BOOL enableRate	是否可以更改播放速率
@property NSInteger numberOfLoops	重復播放次數，為0時只播放一次，小於0時為無限播放，大於0時表示循環次數
@property(readonly) NSDictionary *settings	音頻播放次數信息，只讀
@property(readonly) NSUInteger numberOfChannels	與音頻播放器相關聯的聲音通道的數量。（只讀）
@property(nonatomic, copy) NSArray *channelAssignments	與音頻播放器相關AVAudioSessionChannelDescription對象數組
@property(readonly) NSTimeInterval duration	播放時長
@property NSTimeInterval currentTime	當前播放時長
@property(readonly) NSTimeInterval deviceCurrentTime	輸出設備播放音頻的時間，注意如果播放中被暫停此時間也會繼續累加
@property(readonly) NSURL *url	音頻文件路徑，只讀
@property(readonly) NSData *data	音頻數據，只讀
@property(getter=isMeteringEnabled) BOOL meteringEnabled	否啟用音頻測量，默認為NO，一旦啟用音頻測量可以通過updateMeters方法更新測量值
對象方法	描述
- (instancetype)initWithContentsOfURL:(NSURL *)url  error:(NSError **)outError	使用文件URL初始化播放器，注意這個URL不能是HTTP URL，AVAudioPlayer不支持加載網絡媒體流，只能播放本地文件
- (instancetype)initWithData:(NSData *)data error:(NSError **)outError	使用NSData初始化播放器，注意使用此方法時必須文件格式和文件后綴一致，否則出錯，所以相比此方法更推薦使用上述方法 或- (instancetype)initWithData:(NSData *)data fileTypeHint:(NSString *)utiString error:(NSError **)outError方法進行初始化
- (BOOL)play	播放音頻文件
- (BOOL)playAtTime:(NSTimeInterval)time	在指定的時間開始播放音頻
- (void)pause	暫停播放
- (void)stop	停止播放
- (BOOL)prepareToPlay	將音頻文件加載到緩沖區
- (float)averagePowerForChannel:(NSUInteger)channelNumber	獲得指定聲道的分貝平均值，注意如果要獲得分貝平均值必須在此之前調用updateMeters方法
- (float)peakPowerForChannel:(NSUInteger)channelNumber	獲得指定聲道的分貝峰值，注意如果要獲得分貝峰值必須在此之前調用updateMeters方法
- (void)updateMeters	更新音頻測量值，注意如果要更新音頻測量值必須設置meteringEnabled為YES，通過音頻測量值可以即時獲得音頻分貝等信息
代理方法	說明
- (void)audioPlayerDidFinishPlaying:(AVAudioPlayer *)player successfully:(BOOL)flag	播放完成后調用，在這里可以進行一些屬性的設置
- (void)audioPlayerDecodeErrorDidOccur:(AVAudioPlayer *)player error:(NSError *)error	音頻解碼發生錯誤

AVAudioPlayer的使用比較簡單：

1、初始化AVAudioPlayer對象，通常指定本地文件路徑

2、設置播放器屬性，例如播放次數，音量大小，設置代理等

3、開始播放，調用play方法

下面就是AVAudioPlayer實現的一個簡單播放器，它播放本地的音頻文件，實現了播放、暫停、顯示播放進度，現實播放時間等功能：

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

@interface JZViewController() <AVAudioPlayerDelegate>

@property (nonatomic, strong) AVAudioPlayer * audioPlayer;
@property (nonatomic, strong) UIImageView * imageView;
@property (nonatomic, strong) UIProgressView * progressView;
@property (nonatomic, strong) UILabel * timeLabel;
@property (nonatomic, strong) UILabel * currenttimeLabel;
@property (nonatomic, assign) NSTimer * timer;
@property (nonatomic, assign) int intTime;
@property (nonatomic, assign) int timeNum;
@property (nonatomic, assign) UIButton * button;

@end

@implementation JZViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    self.title = @"禮物"; //播放音頻為 禮物.mp3 鋼琴曲
    self.view.backgroundColor = [UIColor whiteColor];
    
    [self.view addSubview:self.imageView];
    
    [self initView];
}

//界面初始化，添加一個view、一個進度條、3個label、一個button
- (void)initView
{
    UIView * view = [[UIView alloc] initWithFrame:CGRectMake(0, [UIScreen mainScreen].bounds.size.height - 150, [UIScreen mainScreen].bounds.size.width, 150)];
    view.backgroundColor = [UIColor colorWithRed:246 / 255.0 green:246 / 255.0 blue:246 / 255.0 alpha:0.9];
    view.alpha = 0.8f;
    [self.view addSubview:view];

    UIProgressView * progressView = [[UIProgressView alloc] initWithFrame:CGRectMake(40, 50, [UIScreen mainScreen].bounds.size.width - 80, 0)];
    self.progressView = progressView;
    [view addSubview:progressView];
    
    UILabel * timeLabel = [[UILabel alloc] initWithFrame:CGRectMake([UIScreen mainScreen].bounds.size.width - 40, 40, 40, 20)];
    timeLabel.backgroundColor = [UIColor clearColor];
    timeLabel.font = [UIFont systemFontOfSize:11];
    timeLabel.textAlignment = NSTextAlignmentCenter;
    self.timeLabel = timeLabel;
    [view addSubview:timeLabel];
    
    UILabel * currentTimeLabel = [[UILabel alloc] initWithFrame:CGRectMake(0, 40, 40, 20)];
    currentTimeLabel.backgroundColor = [UIColor clearColor];
    currentTimeLabel.font = [UIFont systemFontOfSize:11];
    currentTimeLabel.textAlignment = NSTextAlignmentCenter;
    self.currenttimeLabel = currentTimeLabel;
    [view addSubview:currentTimeLabel];
    
    UILabel * label = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, [UIScreen mainScreen].bounds.size.width, 50)];
    label.backgroundColor = [UIColor clearColor];
    label.text = @"禮物";
    label.textAlignment = NSTextAlignmentCenter;
    [view addSubview:label];
    
    UIButton * button = [[UIButton alloc] initWithFrame:CGRectMake([UIScreen mainScreen].bounds.size.width / 2 - 30, 70, 60, 60)];
    button.backgroundColor = [UIColor clearColor];
    [button setImage:[UIImage imageNamed:@"start.jpg"] forState:UIControlStateNormal];
    [button addTarget:self action:@selector(clickButton:) forControlEvents:UIControlEventTouchUpInside];
    self.button = button;
    button.tag = 10;
    [view addSubview:button];
}

//初始化imageView，添加背景圖片
- (UIImageView *)imageView
{
    if(!_imageView){
        UIImage * image = [UIImage imageNamed:@"sjz.jpg"];
        UIImageView * imageView = [[UIImageView alloc] initWithImage:image];
        imageView.frame = [UIScreen mainScreen].bounds;
        _imageView = imageView;
    }
    return _imageView;
}

//懶加載，創建audioPlayer
- (AVAudioPlayer *)audioPlayer
{
    if(!_audioPlayer){
        NSString * urlStr = [[NSBundle mainBundle] pathForResource:@"禮物.mp3" ofType:nil];
        NSURL * url = [NSURL fileURLWithPath:urlStr];
        NSError * error = nil;
        _audioPlayer = [[AVAudioPlayer alloc] initWithContentsOfURL:url error:&error];
        //設置播放屬性
        _audioPlayer.numberOfLoops = 0;
        _audioPlayer.delegate = self;
        [_audioPlayer prepareToPlay];  //加載音頻文件到緩存
        
        
        if(error){
            NSLog(@"初始化播放器過程發生錯誤，錯誤信息:%@", error.localizedDescription);
            return nil;
        }
        
    }
    return _audioPlayer;
}

//點擊button后調用的方法，播放、暫停音樂
- (void)clickButton:(UIButton *)sender
{
    if(sender.tag == 10){
        sender.tag = 20;
        [sender setImage:[UIImage imageNamed:@"stop.jpg"] forState:UIControlStateNormal];
        [self.audioPlayer play];
        self.timer.fireDate = [NSDate distantPast];
    }else{
        sender.tag = 10;
        [sender setImage:[UIImage imageNamed:@"start.jpg"] forState:UIControlStateNormal];
        [self.audioPlayer pause];
        self.timer.fireDate = [NSDate distantFuture];
    }
}

//初始化定時器
- (NSTimer *)timer
{
    if(!_timer){
        _timer = [NSTimer scheduledTimerWithTimeInterval:1.0f target:self selector:@selector(updateTimeAddProgress) userInfo:nil repeats:YES];
        self.timeNum = (int)self.audioPlayer.duration;
    }
    return _timer;
}

//定時器的調用方法，在這里更新進度條，並且更新時間
- (void)updateTimeAddProgress
{
    float progress = self.audioPlayer.currentTime / self.audioPlayer.duration;
    [self.progressView setProgress:progress animated:YES];
    
    self.intTime++;
    NSString * str = [NSString stringWithFormat:@"%.2d:%.2d", self.intTime / 60, self.intTime % 60];
    self.currenttimeLabel.text = str;
    
    self.timeNum--;
    NSString * strTime = [NSString stringWithFormat:@"%.2d:%.2d", self.timeNum / 60, self.timeNum % 60];
    self.timeLabel.text = strTime;
}

//代理方法，做一些播放完成后的處理，刪除掉定時器，button圖片的更改、停止音樂播放等
- (void)audioPlayerDidFinishPlaying:(AVAudioPlayer *)player successfully:(BOOL)flag
{
    self.intTime = 0;
    [self.audioPlayer stop];
    [self.timer invalidate];
    self.timer = nil;
    
    self.button.tag = 10;
    [self.button setImage:[UIImage imageNamed:@"start.jpg"] forState:UIControlStateNormal];
}

@end