Using existing SDKs

Hey All!
Little background I have built many windows desktop apps with Xojo in the past. Today I decided I wanted to create an iPad POS app that uses Square POS SDKs and APIs. The main reason I want to build this out is I own a pizzeria that uses square. Square is terrible at customizing pizzas and it causes extra training for staff and the online ordering for customers is clunky and ugly. As a result, I want to build a POS that makes it easier for my pizzeria to operate but still using Square at its heart.

That said, I am on here because I have never built an iOS app either using Xcode or Xojo but I know I will need to use both SDKs and APIs to get a lot of the core functions in.

I am hoping to lean on some folks here to help me get these imported/plugged-in/accessible via the Xojo Project.

Does anyone have any good starting points for implementing existing SDKs & APIs for beginners?

Much appreciated.