Simplifying the KVO'ing of the loaded property in CocoaLibSpotify

gistfile1.m

/*
Problem:

SPPlaylistContainer asynchronously loads a list of playlists. Once it has the list, 
each playlist asynchronously loads metadata such as its name and track listing.

This can be a pain to observe with KVO, and firing NSNotifications every time a 
property in this huge tree changes is absurd when KVO already provides this 
functionality. To augment this, I suggest the following API.
*/

/** Call the provided callback block when all passed items are loaded.
 
 The callback block will be triggered immediately if no items are provided 
 or all provided items are already loaded.
 
 @param items An array of items conforming to the `SPAsyncLoading` protocol.
 @param block The block to call when all given items are loaded.
 */
+(void)waitUntilLoaded:(NSArray *)items then:(void (^)(NSArray *))block;


-(void)seachForPlaylist {

    NSString *targetPlaylistName = @"My Awesome Playlist";

    SPPlaylistContainer *container = [[SPSession sharedSession] userPlaylists];

    [SPAsyncLoadingObserver waitUntilLoaded:[NSArray arrayWithObject:container]
                                       then:^(NSArray *loadedItems) {

        // Container is loaded - wait for playlists to load
        [SPAsyncLoadingObserver waitUntilLoaded:container.flattenedPlaylists
                                           then:^(NSArray *loadedPlaylists) {

            // All playlists are loaded
            NSArray *names = [loadedPlaylists valueForKey:@"name"];
            if ([names containsObject:targetPlaylistName])
                NSLog(@"Playlist exists!");
        }];
    }];
}

I started playing with CocoaLibSpotify just yesterday and I'm already feeling this pain, so +1 from me. I appreciate this gist is a month old,

If you have a moment, I'd really appreciate a canonical code example for asynchronously getting the full list of playlists with metadata. I'm new to KVO, so whatever I put together will likely be horrible. Might be a good thing to stick in the README.

Thanks for CocoaLibSpotify, in any case!

That was meant to say "I appreciate this gist is a month old, are you still planning to implement this API?"

Hi!

Yes, the API has been implemented in the 2.0-dev branch of CocoaLibSpotify, which will be merged to master in a few days. If you check out the 2.0-dev branch, you'll find a brief example in the README and good examples of how to use it in the unit tests.