Getting The Corresponding MPMediaItem With MPMediaItemPropertyPersistentID

Question

I need to retrieve the corresponding MPMediaItem with the persistent ID I stored using NSUserDefaults. My current way of doing this is to get all the MPMediaItems, loop through them, and find out the one that has the same persistent ID that I stored. I think this is a really bad performance, so is there an existing method in getting the MPMediaItem with the persistent ID that I have? I checked the documentation of Apple, but I was unable to find one.

Answer 1

You can get better than linear performance by looking up your MPMediaItem the items with a unique ID query:

MPMediaQuery*   query = [MPMediaQuery songsQuery];  // general songs query

MPMediaPropertyPredicate* pred = [MPMediaPropertyPredicate predicateWithValue:persistentID
                                                                  forProperty:MPMediaItemPropertyPersistentID];
// narrow the query down to just items with that ID
[query addFilterPredicate:pred];

// now get items (there should be only one):
MPMediaItem *item = [query.items firstObject];