Swift

Hacking with Swift by Paul Hudson teaches Swift and iOS development through a long list of complete projects, each introducing a few new APIs, and it is free to read online. It is the most complete starting point here. Build an iOS App with SwiftUI is the official getting-started tutorial on swift.org and is shorter, a good way to see SwiftUI's declarative style first.

Developing iOS Apps with SwiftUI is Stanford's CS193p course, with lecture videos and assignments that build apps such as a memory card game and cover MVVM architecture. Retro first-person shooter from scratch is Nick Lockwood's Retro Rampage, a GitHub tutorial series that builds a Wolfenstein 3D style raycasting engine in Swift without game frameworks, which is a good lesson in rendering and math rather than UIKit.

A sensible order is the swift.org SwiftUI tutorial, then Hacking with Swift, then CS193p, with Retro Rampage as a side project.