Online Courses
This is a solid, free course by Paul Hudson on getting started with Swift and SwiftUI. It is targetted at beginners but it is interesting enough for people who have experience in other languages. It is well paced and focused and there are plenty of opprotunities to take the lessons deeper with challenge exercises.
I've followed three of Sean's courses. All of them are solid. He walks though his philosophy on building applications and real-world trade offs. He makes mistakes and then shows how he fixes them. He talks quickly but that gives the courses energy and the learner can always scrub back and review.
iOS Dev Job Interview Practice - Take Home Project
Get exposed to non-storyboard UIKit in making an app to list followers on GitHub. It is modeled after a take-home project for an interview.
Dub Dub Grub
This is a SwiftUI app that uses MapKit and CloudKit. I went back to this one when I submitted my first app to the Apple app store as Sean walks through that process in real-time.
WidgetKit
Do you want to make widgets or use the dynamic island, this course shows you how.
Stanford
The course is from 2021 and is a little dated, but is a nice step after 100 Days of SwiftUI. Professor Paul Hegarty is an engaging lecture who walks through app architecture and app creation. There is a magic moment in one of the early lectures where a single line of coded is added and suddenlt all of the UI works. Be warned that this is a college course and it moves quickly, but it is worth it.
Udemy
Angela Yu
This bootcamp course is aimed at iOS13. It gives an overview of a lot of Apple frameworks. I think it is still useful.