How to incorporate Framework SwiftUI

Question

We can use Framework SwiftUI only from iOS 13.0+. So how to incorporate this framework from the deployment Target 10.0 or at least 12.0.

Answer 1

Although @DenFav is absolutely right - supporting deployment target below iOS 13 with SwiftUI is a pain, but it is possible.

Steps:

1. Link the framework weakly (I used this answer):

   Adding -weak_framework SwiftUI to Other Linker Flags fixed my issue

2. Wrap all SwiftUI calls with canImport (see answer):

   #if canImport(SwiftUI) && canImport(Combine)

This will allow you to build and archive with deployment target < iOS 13.

Optional:

Now the question is: how to deal with viewModels. I solved this with my own implementation. You can check the solution in the public repo of Ruuvi Station. Note: the code is complex (VIPER), that's why I'll shortly describe the main ideas.

The viewModel implementation is in Classes/Presentation/Binding.

I'm using these viewModels, wrapping them with ObservableObject for SwiftUI.

You can still observe changes made in SwiftUI code.

The result is: iOS 13 uses SwiftUI code for Presentation Layer, while iOS 12 and lower is using traditional UIKit code.

The viewController is responsible for determining if SwiftUI code can be used.