How unique is MPMediaItemPropertyPersistentID? Will it even work when synching the list of IDs to another device connected to the same iTunes Account?
I want to implement a iCloud synchronized playlist solution which stores the IDs as a list and I need to know if this will be possible.
As per the documentation (emphasis mine)...
The value of the MPMediaItemPropertyPersistentID identifier persists across application launches and across syncs that do not change the sync status of the media item. The value is not guaranteed to persist across a sync/unsync/sync cycle.
As such, given that it won't even persist on this basis I'd be surprised if it persisted across devices in a sufficiently robust manner, if at all.