Board Thread:General Discussion/@comment-98.214.22.120-20150513002632/@comment-4189499-20150515003729

They have to rewrite the levels for your phone and tablet from the code used for the Facebook levels. The different devices use different programming languages, you see, and therefore the game can't be moved easily between platforms. Also, the iOS app store takes a while to approve new updates to apps before they reach consumers, unlike Facebook, meaning it takes even longer for the levels to appear.