Where to start - Custom Music from User's library (iOS) ?

Are there any plugins/tutorials/tools/etc. that enables the user to choose music from their library on iOS?  Kind of like an in-App music player that goes directly to iTunes library.

I think this is more advanced so I may not tackle it.  But while I’m posting on the subject, my app will play while the music is playing in background.  But when the App starts a sound effect, then the background music switches off , on my iPhone/iPad.  Is there a way (simple :mellow: ?) to keep both sound effects and whatever song maybe playing in background on iTunes.

Thanks