From UIKit to SwiftUI

[ladislas]

I'll start :) (not sure if it's the right place though)

I have an app in UIKit and I want to start adding SwiftUI interfaces and slowly replace most of the UIKit stuff.

It is better to:

• add SwiftUI to UIKit through UIHostingController
• or wrap the "entire app" in UIViewRepresentable

What would be the pros and cons?

And if I'm not asking the right question, please let me know, I'm eager to learn :)

[alicerunsonfedora]

I can't really answer for iOS, but I can at least tell you the migration process for me with SwiftUI on macOS and AppKit. I often use the hosting controller more than the view representable since it was relatively easy to integrate and work with, and it worked well for what I wanted to accomplish. I was able to migrate my preference panes to SwiftUI from storyboards with a hosting controller attached to some views in the Preferences Swift package (https://github.com/sindresorhus/Preferences) and it worked pretty well.

[sindresorhus]

I also went with the former, wrapping SwiftUI views in hosting views. Then you can slowly move to SwiftUI, view by view. For example, in my Dato app, I started by rewriting my preferences window views in SwiftUI (the window itself still being NSWindow), while the rest of the app was still AppKit. Then I rewrote the NSMenuItem items for the calendar events and time zones from using attributed strings to using SwiftUI view wrapped in hosting views. I would use UIViewRepresentable when I need to use built-in AppKit/UIKit views in SwiftUI, for example, an image picker or share sheet.

You can see an example here where I partly moved to SwiftUI (different app): sindresorhus/Blear@a991c6b

[ladislas]

Thank you both for your feedback!

We've started with the former approach and it works well!

One thing we haven't figure out yet (but tbh we did not spend that much time on it) is:

• you have a ViewController
• you push a new SwiftUI View wrapped in a UIHostingController
• then from that view we want to push a new SwiftUI view

Our first attempt was using NavigationLink but it did not end well.

What's the best way to handle this case? Should we have a centralized navigation logic?

[sindresorhus]

I would keep using the normal view controller view presentation methods. Just inject the current view controller into the SwiftUI view using an EnvironmentKey.

Example (not view controller, but same concept):

• https://github.com/sindresorhus/Blear/blob/59dc6f42292e73678779ddc06c1e0f7a19878bff/Action%20Extension/ActionViewController.swift#L11-L12
• https://github.com/sindresorhus/Blear/blob/0021eade7f8439497b761dd389270e2cc667e679/Blear/Utilities.swift#L1048-L1060