CODEWITHSUNDEEP
iosswiftswiftuiuiscenedelegate
Michel
Michel

Reputation: 11755

SwiftUI, changing a view from scene(:continue

In a SwiftUI app, I am facing a new challenge and hope someone can give me some hints or guidance. The mechanisms I have seen up to now to communicate between the parts of an app don't seem to quite fit here. But it is probably due to my still limited experience with SwiftUI.

First here is the relevant code:

class SceneDelegate {
  ... lot of code irrelevant to the question ...
  func scene(_ scene: UIScene, 
             continue userActivity: NSUserActivity) {
      ... useful things happening for the app ...
      // Now the view should change ... by some mechanism.
      // This is the point of the question.
  }
}

and:

struct ContentView: View {
    ... lot of code irrelevant to the question ...
    var body: some View {
        VStack {
          ... code to draw the view ...
        }
        ... more code to draw the view ...
    }
}

Second, my question is: how do I make my view to redraw itself, after processing has been performed inside scene(:continue ?

I had in mind some ideas, to do things in the scene(:continue function which would influence the drawing of the view.

Unfortunately, when trying to implement, I realized the code drawing the view was executed before the scene(:continue function. Therefore I need some other mechanism (notification like, bindings like, or ??) to have the view redrawn.

Is there a good practice or standard way of doing that?

Upvotes: 1

Views: 950

Answers (1)

Asperi
Asperi

Reputation: 258611

It would be appropriate to use EnvironmentObject in this scenario

class AppState: ObservableObject
   @Published var someVar: Sometype
}

class SceneDelegate {
  let appState = AppState()

  func scene(_ scene: UIScene, 
             continue userActivity: NSUserActivity) {

     // ... other code 
     appState.someVar = ... // modify
  }
}

  func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {

     // .. other code
    let contentView = ContentView()
        .environmentObject(appState)
     //
  }
}

struct ContentView: View {
    @EnvironmentObject var appState

    var body: some View {
        VStack {
            // ... other code
            appState.someVar // use here as needed
        }
    }
}

Upvotes: 2

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