[SwiftUI] Data passing + Observation

[rayx (Huan Xiong)]

@mikuha

In searches for SwiftUI examples on Google and Github, the examples I found simply bound primitive data types from the ViewModel. I haven't found good realistic examples. My search terms may just be incorrect.

Do you mean how to pass data between two models of reference type? I couldn't find examples for SwiftUI 5 either, but there should be many for SwiftUI 4.

Note: ObservableObject is a Combine API, not SwiftUI API. Your question is actually a typical Combine use case. I think you have better chance to find examples in Combine tutorials.

@mikuha

I did intend @Observable from Observation as I am using Swift 5.9 features. From the WWDC they seem to treat the new @Observable macro practically the same as conformance to ObservableObject.

Ah, then I think you misunderstood it. The new Observable APi is Combine free, so you shouldn't use @Published or Combine API. I'm also curious what's the recommended way to pass data between two objects in the new API. I guess it might be withMutation()[ [Second review] SE-0395: Observability - #48 by Philippe_Hausler], but in my opinion it's not as easy to use as the Combine API (I'd be glad to proved wrong). Another possibility is withObservationTracking()[ withObservationTracking(_:onChange:) | Apple Developer Documentation], but I doubt it.

@mikuha

However, I don't mind using the older method.

I think it will be easier to start with the old API. But if you are not in hurry, it would be worth learning the new API. That said, it's important to have a good understanding of the solution to this question.

@mikuha

After exploring some more, I realise that if the LocationManager has a completion closure that returns the location, it will simplify the bindings. That way, the LocationManager does not need to be Observable. If it was updating constantly with the user's live location, making the location Observable may be better.

If I understand it correctly, you meant you can avoid the original question by using just one Observable, right? But I still think it's important to figure out the original question.