Question

How can I search the iPod Library in the same manner as the iOS Music application? I want to make general queries that return results for each Artists, Albums, and Songs. For instance, if I search Kenny Chesney I want the songs query to return all Kenny Chesney songs (and any songs titles or albums that contain Kenny Chesney in them.) When I make this query and a predicate for each property (song title, album title, artist name), an empty array returns.

Here is a bit of code that may give you a better idea of what I am attempting to accomplish:

MPMediaPropertyPredicate *songPredicate =
[MPMediaPropertyPredicate predicateWithValue:searchText
                                 forProperty:MPMediaItemPropertyTitle
                              comparisonType:MPMediaPredicateComparisonContains];

MPMediaPropertyPredicate *albumPredicate =
[MPMediaPropertyPredicate predicateWithValue:searchText
                                 forProperty:MPMediaItemPropertyAlbumTitle
                              comparisonType:MPMediaPredicateComparisonContains];

MPMediaPropertyPredicate *artistPredicate =
[MPMediaPropertyPredicate predicateWithValue:searchText
                                 forProperty:MPMediaItemPropertyArtist
                              comparisonType:MPMediaPredicateComparisonContains];

MPMediaQuery *songsQuery = [MPMediaQuery songsQuery];
[songsQuery addFilterPredicate:songNamePredicate];
[songsQuery addFilterPredicate:artistNamePredicate];
[songsQuery addFilterPredicate:albumNamePredicate];

NSLog(@"%@", [songsQuery items]);

I have this working by running the query with each predicate separately but this seems very inefficient!

Answer 1

Combining your predicates this way makes it like “AND” relationship. It means that you are querying for a song that has title, album and name all are matching the search text.

To achive what you are trying to do, you should run 3 queries and combining the results in a proper way.

If you run:

MPMediaPropertyPredicate *artistPredicate =
[MPMediaPropertyPredicate predicateWithValue:searchText
                                 forProperty:MPMediaItemPropertyArtist
                              comparisonType:MPMediaPredicateComparisonContains];

NSSet *predicates = [NSSet setWithObjects: artistPredicate, nil];

MPMediaQuery *songsQuery =  [[MPMediaQuery alloc] initWithFilterPredicates: predicates];

NSLog(@"%@", [songsQuery items]);

This will return you with artists matching your search.
The same you should do for songs and albums.

If you this this is slow, you may retrieve all the media at once and filter it manually:

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];
    /* Filter found songs here manually */
}