Most of the interaction in Touchgram occurs in the iMessage app extension. There is a full host app as well.
I'm about to add a number of IAP for tool subscriptions as well as buying digital currency, to pay for assets.
Can I use StoreKit inside the extension or does the workflow for handling purchases and receipt validation all have to happen inside my host app?
Note
Touchgram is probably the most complex iMessage app extension ever built (especially when I wrap v1.3) - it's effectively a full Keynote-level layout system plus gesture recognition plus exposing SpriteKit features such as shaders, animations & particles... all inside iMessage...to send interactive messages. There is a lot happening in that extension! What's currently in the live app on the store is a long way behind what's due to be released after WWDC.