播放iPod Library歌曲

一、简述　　

　　对于影音娱乐类应用来说播放设备本地音乐是一项比较实用的功能，市面上的音乐播放器大多也都支持该功能。Apple提供两种方式来访问本地音乐库，分别是 MPMediaQuery 和 MPMediaPickerController。MPMediaPickerController 是一个已定制好UI的控件，为了满足自定义需求，通常我们使用 更强大的 MPMediaQuery 来获取本地音乐。

本文提供一个Demo简单展示如何使用 MPMediaQuery 获取本地音乐信息并使用 AVAudioPlayer 播放。如下图：

二、代码示例

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

@interface ViewController ()<UITableViewDataSource,UITableViewDelegate,AVAudioPlayerDelegate>
@property (nonatomic, strong) AVAudioPlayer *audioPlayer;
@property (nonatomic, strong) MPMediaQuery  *mediaQuery;
@property (nonatomic, strong) UITableView   *mediaTableView;
@property (nonatomic, assign) NSInteger     playingIndex;
@end

@implementation ViewController
- (UITableView *)mediaTableView{
    if (!_mediaTableView) {
        _mediaTableView = [[UITableView alloc] initWithFrame:self.view.bounds style:UITableViewStyleGrouped];
        _mediaTableView.delegate = self;
        _mediaTableView.dataSource = self;
    }
    return _mediaTableView;
}

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    self.playingIndex = NSIntegerMax;
    self.mediaQuery = [MPMediaQuery songsQuery];
    [self.view addSubview:self.mediaTableView];

    UILabel *header = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, CGRectGetWidth(self.view.bounds),64.0)];
    header.text = @"iPod Library";
    header.textColor = [UIColor brownColor];
    header.textAlignment = NSTextAlignmentCenter;
    header.font = [UIFont systemFontOfSize:18.0];
    [self.mediaTableView setTableHeaderView:header];

    UIButton *footer = [UIButton buttonWithType:UIButtonTypeCustom];
    footer.frame = CGRectMake(0, 0, CGRectGetWidth(self.view.bounds), 32.0);
    [footer setTitle:@"stop" forState:UIControlStateNormal];
    footer.titleLabel.font = [UIFont systemFontOfSize:18.0];
    [footer setTitleColor:[UIColor brownColor] forState:UIControlStateNormal];
    [footer addTarget:self action:@selector(stop) forControlEvents:UIControlEventTouchUpInside];
    [self.mediaTableView setTableFooterView:footer];
}

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

#pragma mark - Action
/**
 *  播放音频
 *
 *  @param itme <#itme description#>
 */
- (void)playMediaWithItem:(MPMediaItem *) itme{
    self.audioPlayer = [[AVAudioPlayer alloc] initWithContentsOfURL:itme.assetURL error:nil];
    self.audioPlayer.delegate = self;
    [self.audioPlayer prepareToPlay];
    [self.audioPlayer play];
}

/**
 *  stop
 */
- (void)stop{
    if (self.audioPlayer.playing) {
        [self.audioPlayer stop];
        self.playingIndex = NSIntegerMax;
        [self.mediaTableView reloadData];
    }
}

#pragma mark - UITableViewDataSource
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView{
    return 1;
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section{
    return self.mediaQuery.items.count;
}

- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath{
    return 66.0;
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{
    static  NSString *cellIdentifier = @"ipodMusicCell";
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:cellIdentifier];
    if (!cell) {
        cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:cellIdentifier];
    }
    MPMediaItem *item = self.mediaQuery.items[indexPath.row];
    cell.textLabel.text = item.title;
    cell.textLabel.textColor = [UIColor brownColor];
    cell.detailTextLabel.text = item.artist;
    cell.detailTextLabel.textColor = [UIColor brownColor];
    cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator;
    cell.tintColor = [UIColor brownColor];

    if (indexPath.row == self.playingIndex) {
        cell.textLabel.textColor = [UIColor redColor];
        cell.detailTextLabel.textColor = [UIColor redColor];
        cell.accessoryType = UITableViewCellAccessoryCheckmark;
        cell.tintColor = [UIColor redColor];
    }
    return cell;
}

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath{
    MPMediaItem *item = self.mediaQuery.items[indexPath.row];
    [self playMediaWithItem:item];

    self.playingIndex = indexPath.row;
    [self.mediaTableView reloadData];
}

#pragma mark - AVAudioPlayerDelegate
- (void)audioPlayerDidFinishPlaying:(AVAudioPlayer *)player successfully:(BOOL)flag{
    if (player == self.audioPlayer) {
        self.playingIndex ++; //自动下一曲
        if (self.playingIndex < self.mediaQuery.items.count) {
            [self playMediaWithItem:self.mediaQuery.items[_playingIndex]];
        } else {
            self.playingIndex = 0;
            [self playMediaWithItem:[self.mediaQuery.items firstObject]];
        }
        [self.mediaTableView reloadData];
    }
}
@end