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访问iPod Library及MPMusicPlayerController

时间：2014-02-16 05:41:32      阅读：491      评论：0      收藏：0      [点我收藏+]

1.访问音乐库的两种方法，

（只能访问音频文件，如music，podcast，audiobook等）

2.MPMusicPlayerController的使用

有两种播放器可以选择，一种是application　music　player，另外一种是iPod　music　player。

第一种播放器是一种内部播放器，当程序对出后停止播放；而第二种播放器则与iPod播放器内的信息相关，退出之后不会停止播放。获取方式如下：

  • + applicationMusicPlayer
  • + iPodMusicPlayer

播放之前需要设置播放器的播放队列

  • – setQueueWithQuery:
  • – setQueueWithItemCollection:

管理播放模式和播放状态的一些属性

  •   currentPlaybackTime  property
  •   nowPlayingItem  property
  •   playbackState  property
  •   repeatMode  property
  •   shuffleMode  property
  •   volume  property

播放状态　MPMusicPlaybackState

 

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enum {
 
   MPMusicPlaybackStateStopped,
 
   MPMusicPlaybackStatePlaying,
 
   MPMusicPlaybackStatePaused,
 
   MPMusicPlaybackStateInterrupted,
 
   MPMusicPlaybackStateSeekingForward,
 
   MPMusicPlaybackStateSeekingBackward
 
};
 
typedef NSInteger MPMusicPlaybackState;

 

播放控制方法

  • – play
  • – pause
  • – stop
  • – beginSeekingForward
  • – beginSeekingBackward
  • – endSeeking
  • – skipToNextItem
  • – skipToBeginning
  • – skipToPreviousItem

播放状态发生变化时可以发送通知

  • – beginGeneratingPlaybackNotifications
  • – endGeneratingPlaybackNotifications

MPMusicPlayerControllerPlaybackStateDidChangeNotification

可以通过该通知来改变播放按钮的样式

MPMusicPlayerControllerNowPlayingItemDidChangeNotification

MPMusicPlayerControllerVolumeDidChangeNotification

具体步骤

１.注册和开始发送通知

 

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Listing 2-1  Registering for and activating music player notifications
NSNotificationCenter *notificationCenter = [NSNotificationCenter defaultCenter];
  
[notificationCenter
    addObserver: self
    selector:    @selector (handle_NowPlayingItemChanged:)
    name:        MPMusicPlayerControllerNowPlayingItemDidChangeNotification
    object:      musicPlayer];
  
[notificationCenter
    addObserver: self
    selector:    @selector (handle_PlaybackStateChanged:)
    name:        MPMusicPlayerControllerPlaybackStateDidChangeNotification
    object:      musicPlayer];
  
[musicPlayer beginGeneratingPlaybackNotifications];
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Listing 2-2  Unregistering and deactivating music player notifications
[[NSNotificationCenter defaultCenter]
    removeObserver: self
    name:           MPMusicPlayerControllerNowPlayingItemDidChangeNotification
    object:         musicPlayer];
  
[[NSNotificationCenter defaultCenter]
    removeObserver: self
    name:           MPMusicPlayerControllerPlaybackStateDidChangeNotification
    object:         musicPlayer];
  
[musicPlayer endGeneratingPlaybackNotifications];
２.创建并配置一个Music　Player 

 

 

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Listing 2-3  Creating an application music player
MPMusicPlayerController* appMusicPlayer =
    [MPMusicPlayerController applicationMusicPlayer];
  
[appMusicPlayer setShuffleMode: MPMusicShuffleModeOff];
[appMusicPlayer setRepeatMode: MPMusicRepeatModeNone];
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Listing 2-4  Creating an iPod music player
MPMusicPlayerController* iPodMusicPlayer =
    [MPMusicPlayerController iPodMusicPlayer];
  
if ([iPodMusicPlayer nowPlayingItem]) {
    // Update the UI (artwork, song name, volume indicator, etc.)
    //        to reflect the iPod state
}
３.设置播放队列

 

 

  • – setQueueWithQuery:
  • – setQueueWithItemCollection:
４.控制播放

3.MPMediaPickerController的使用

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- (IBAction)addSongsToMusicPlayer:(id)sender
{
    MPMediaPickerController *mpController = [[MPMediaPickerController alloc] initWithMediaTypes:MPMediaTypeMusic];
    mpController.delegate = self;
    mpController.prompt = @"Add songs to play";
    mpController.allowsPickingMultipleItems = YES;
     
    [self presentModalViewController:mpController animated:YES];
    [mpController release];
}

主要是设置代理和选择多媒体类型，然后通过代理方法来获取选中的歌曲

 

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#pragma mark - Media Picker Delegate Methods
 
- (void)mediaPicker:(MPMediaPickerController *)mediaPicker didPickMediaItems:(MPMediaItemCollection *)mediaItemCollection
{
    [self.musicPlayer setQueueWithItemCollection:mediaItemCollection];
    [self dismissModalViewControllerAnimated:YES];
}
 
- (void)mediaPickerDidCancel:(MPMediaPickerController *)mediaPicker
{
    [self dismissModalViewControllerAnimated:YES];
}

 

4.MPMediaItem

用此方法来获取item的metadata
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- (id) valueForProperty: (NSString *) property

NSString *const MPMediaItemPropertyTitle;                   

NSString *const MPMediaItemPropertyAlbumTitle;              

NSString *const MPMediaItemPropertyArtist;                 

 

 

5.MPMediaItemCollection

collection是一组有序的item集合，可用同样的方法来获取collection的metadata
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- (id) valueForProperty: (NSString *) property
创建
  • + collectionWithItems:
  • – initWithItems:

属性

  •   items  property
  •   representativeItem  property
  •   count  property
  •   mediaTypes  property

6.MPMediaPlaylist

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MPMediaQuery *myPlaylistsQuery = [MPMediaQuery playlistsQuery];
NSArray *playlists = [myPlaylistsQuery collections];
  
for (MPMediaPlaylist *playlist in playlists) {
    NSLog (@"%@", [playlist valueForProperty: MPMediaPlaylistPropertyName]);
  
    NSArray *songs = [playlist items];
    for (MPMediaItem *song in songs) {
        NSString *songTitle =
            [song valueForProperty: MPMediaItemPropertyTitle];
        NSLog (@"\t\t%@", songTitle);
    }
}

7.MPMediaQuery

需要设置两个属性: filter  and  grouping type

filter描述查询内容，grouping type 描述返回内容的排列方式

查询可以获取items，也可以获取collections

  • When you ask for items, the query returns a collection containing all the items that match the filter. The items are in “natural” order, meaning that they are ordered as iTunes shows them on the desktop.
  • When you ask for collections, the media query employs not only its filter but also its grouping type.
获取全部歌曲
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MPMediaQuery *everything = [[MPMediaQuery alloc] init];
NSLog(@"Logging items from a generic query...");
NSArray *itemsFromGenericQuery = [everything items];
for (MPMediaItem *song in itemsFromGenericQuery) {
    NSString *songTitle = [song valueForProperty: MPMediaItemPropertyTitle];
    NSLog (@"%@", songTitle);
}
获取名为“Happy the Clown”的艺术家的歌曲
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MPMediaPropertyPredicate *artistNamePredicate =
    [MPMediaPropertyPredicate predicateWithValue: @"Happy the Clown"
                                     forProperty: MPMediaItemPropertyArtist];
  
MPMediaQuery *myArtistQuery = [[MPMediaQuery alloc] init];
[myArtistQuery addFilterPredicate: artistNamePredicate];
  
NSArray *itemsFromArtistQuery = [myArtistQuery items];
多个查找条件，查找名为"Sad the Joker"的艺术家的"Stair Tumbling"专辑
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MPMediaPropertyPredicate *artistNamePredicate =
    [MPMediaPropertyPredicate predicateWithValue: @"Sad the Joker"
                                     forProperty: MPMediaItemPropertyArtist];
  
MPMediaPropertyPredicate *albumNamePredicate =
    [MPMediaPropertyPredicate predicateWithValue: @"Stair Tumbling"
                                     forProperty: MPMediaItemPropertyAlbumTitle];
  
MPMediaQuery *myComplexQuery = [[MPMediaQuery alloc] init];
  
[myComplexQuery addFilterPredicate: artistNamePredicate];
[myComplexQuery addFilterPredicate: albumNamePredicate];
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Listing 4-4  Applying multiple predicates when initializing a media query
NSSet *predicates =
    [NSSet setWithObjects: artistNamePredicate, albumNamePredicate, nil];
  
MPMediaQuery *specificQuery =
    [[MPMediaQuery alloc] initWithFilterPredicates: predicates];
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Listing 4-5  Testing if a property key can be used for a media property predicate
if ([MPMediaItem canFilterByProperty: MPMediaItemPropertyGenre]) {
    MPMediaPropertyPredicate *rockPredicate =
        [MPMediaPropertyPredicate predicateWithValue: @"Rock"
                                         forProperty: MPMediaItemPropertyGenre];
    [query addFilterPredicate: rockPredicate];
}
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Listing 4-6  Using grouping type to specify media item collections
MPMediaQuery *query = [[MPMediaQuery alloc] init];
  
[query addFilterPredicate: [MPMediaPropertyPredicate
                               predicateWithValue: @"Moribund the Squirrel"
                                      forProperty: MPMediaItemPropertyArtist]];
// Sets the grouping type for the media query
[query setGroupingType: MPMediaGroupingAlbum];
  
NSArray *albums = [query collections];
for (MPMediaItemCollection *album in albums) {
    MPMediaItem *representativeItem = [album representativeItem];
    NSString *artistName =
        [representativeItem valueForProperty: MPMediaItemPropertyArtist];
    NSString *albumName =
        [representativeItem valueForProperty: MPMediaItemPropertyAlbumTitle];
    NSLog (@"%@ by %@", albumName, artistName);
  
    NSArray *songs = [album items];
    for (MPMediaItem *song in songs) {
        NSString *songTitle =
            [song valueForProperty: MPMediaItemPropertyTitle];
        NSLog (@"\t\t%@", songTitle);
    }
}
query的一些简便构造方法
bubuko.com,布布扣
专辑封面的使用
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Listing 4-7  Displaying album artwork for a media item
MPMediaItemArtwork *artwork =
    [mediaItem valueForProperty: MPMediaItemPropertyArtwork];
UIImage *artworkImage =
    [artwork imageWithSize: albumImageView.bounds.size];
if (artworkImage) {
    albumImageView.image = artworkImage;
} else {
    albumImageView.image = [UIImage imageNamed: @"noArtwork.png"];
}

访问iPod Library及MPMusicPlayerController

原文：http://blog.csdn.net/u010079532/article/details/19248357
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