I've seen a few posts commenting on the lack of a proper Swift SDK and questions what it would take to build one.
I just came across this project which was recently started by the Kin Foundation team:
https://github.com/kinfoundation/StellarKit
They've completed all of the XDR serialization/deserialization and it looks really clean and complete. If you're an iOS dev this a repo you'll want to follow.
