I've recently been listening to a ton of music on YouTube via iOS. I'd like to be able to start playing a song, go search for another song (while the other song is playing in the background), and add it to the queue of songs. This is very similar to the playlists feature of YouTube itself, with the exception that it's just a local queue and I can add/search while music is playing. I'm looking for a third-party app. Is there such an app?