在Mac OS X上編程訪問照片庫：PhotoKit/Photos Framework for Mac

Question

在Objective-C中，有一個Photos Framework a.k.a. PhotoKit，它使iOS開發人員可以訪問iPhone和iPad上的照片庫並檢索照片/視頻其元數據。

Mac開發人員將如何執行類似的任務？ 看來PhotoKit僅適用於iOS 8.0。是否有相當於Mac OS X的照片框架？

Answer 1

Media Library Framework是去的地方。

用法：

@import MediaLibrary; 

- (void) awakeFromNib 
{ 
    NSDictionary *options = @{ 
    MLMediaLoadSourceTypesKey: @(MLMediaSourceTypeImage), 
    MLMediaLoadIncludeSourcesKey: @[MLMediaSourcePhotosIdentifier] 
    }; 

    MLMediaLibrary *mediaLibrary = [[MLMediaLibrary alloc] initWithOptions:options]; 
    self.mediaLibrary = mediaLibrary; 

    [mediaLibrary addObserver:self 
       forKeyPath:@"mediaSources" 
        options:0 
        context:(__bridge void *)@"mediaLibraryLoaded"]; 

    [mediaLibrary mediaSources]; // returns nil and starts asynchronous loading 
} 

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object 
         change:(NSDictionary *)change context:(void *)context 
{ 
    if (context == (__bridge void *)@"mediaLibraryLoaded") { 
     // Media Library is loaded now, we can access mediaSources 
     MLMediaSource *mediaSource = [self.mediaLibrary.mediaSources objectForKey:@"com.apple.Photos"]; 
    } 
} 

庫背後的概念是，你必須要求它來讀取一個對象，它返回一個空引用的屬性。然後，您使用鍵值觀察者訂閱此屬性，然後等待其加載。然後，你可以用相同的原理檢索下一個孩子等等...

Answer 2

基於皮埃爾˚F答案我顯示的URL的所有照片延長代碼：

- (void)applicationDidFinishLaunching:(NSNotification *)aNotification { 

    NSDictionary *options = @{ 
           MLMediaLoadSourceTypesKey: @(MLMediaSourceTypeImage), 
           MLMediaLoadIncludeSourcesKey: @[MLMediaSourcePhotosIdentifier] 
           }; 

    self.mediaLibrary = [[MLMediaLibrary alloc] initWithOptions:options]; 

    [self.mediaLibrary addObserver:self 
         forKeyPath:@"mediaSources" 
          options:0 
          context:(__bridge void *)@"mediaLibraryLoaded"]; 

    [self.mediaLibrary.mediaSources objectForKey:MLMediaSourcePhotosIdentifier]; 
} 


- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object 
         change:(NSDictionary *)change context:(void *)context 
{ 
    MLMediaSource *mediaSource = [self.mediaLibrary.mediaSources objectForKey:MLMediaSourcePhotosIdentifier]; 

    if (context == (__bridge void *)@"mediaLibraryLoaded") 
    { 
     [mediaSource addObserver:self 
          forKeyPath:@"rootMediaGroup" 
           options:0 
           context:(__bridge void *)@"rootMediaGroupLoaded"]; 

     [mediaSource rootMediaGroup]; 
    } 
    else if (context == (__bridge void *)@"rootMediaGroupLoaded") 
    { 
     MLMediaGroup *albums = [mediaSource mediaGroupForIdentifier:@"TopLevelAlbums"]; 

     for (MLMediaGroup *album in albums.childGroups) 
     { 
      NSString *albumIdentifier = [album.attributes objectForKey:@"identifier"]; 

      if ([albumIdentifier isEqualTo:@"allPhotosAlbum"]) 
      { 
       self.allPhotosAlbum = album; 

       [album addObserver:self 
         forKeyPath:@"mediaObjects" 
          options:0 
          context:@"mediaObjects"]; 

       [album mediaObjects]; 

       break; 
      } 
     } 
    } 
    else if (context == (__bridge void *)@"mediaObjects") 
    { 
     NSArray * mediaObjects = self.allPhotosAlbum.mediaObjects; 

     for(MLMediaObject * mediaObject in mediaObjects) 
     { 
      NSURL * url = mediaObject.URL; 

      NSLog(url.path); 
     } 
    } 
}