Restart SwiftUI rewrite

[stevenzeck]

This PR is a soft restart of rewriting the TestApp using SwiftUI. It's based on the other swiftui branch, but with minimal changes. None of the code that is changed affects the behavior of the UIKit version and thus can be safely merged into develop.

One thing that is changed for the UIKit version is the iOS Deployment Target now being 16.0.

• To switch to the SwiftUI based UI, comment out @UIApplicationMain in AppDelegate.swift and uncomment out @main in TestApp.swift.

[stevenzeck]

@mickael-menu Any thoughts about the iOS Deployment Target? This build will fail unless we change some SwiftUI code to be iOS 14 compatible (if that's even possible), or bump it up to iOS 15+.

[mickael-menu]

Thanks @stevenzeck! We can definitely up the minimum iOS version to 15 or 16 for the Test App. The toolkit must stay at iOS 13 though.

[stevenzeck]

Updated to 16. I'm happy with this now.

[CunningMonkey]

when i try the command "make spm" in your branch, it has error:

ninja@ninja-baidu ~/D/u/TestApp (rewrite-swiftui)> make spm
xcodegen generate
Parsing project spec failed: Invalid version:
make: *** [spm] Error 1

do you know how to fix this?

[stevenzeck]

You should be using make dev for this branch, but both that and make spm should work. What version of xcodegen do you have installed? I'm on 2.42. Since I upgraded the iOS version to 16, it might fail on older versions.