Problem: How to call a SwiftUI View Struct Method from SceneDelegate

Question

Currently I'm the one not getting it.

Problem:

Trying to connect to a View Method from a Scene Delegate e.g.:

class SceneDelegate: UIResponder, UIWindowSceneDelegate {
  var window: UIWindow?

  ...

  func scene(_ scene: UIScene, continue userActivity: NSUserActivity) {
    // guard let contentView = ???? as? ContentView else { return }
    // contentView.callMethod(parameter: true)
  }
}

struct ContentView: View {    
  var body: some View {
    ...
  }

  func callMethode(parameter: Bool) {
    print("called")
  }
}

Any clue how to connect to the View and call a method in-between?

thx Jo

Just don't do it. The communication between views are supposed through data, or combine framework. Don't call the view directly. — E.Coms
– E.Coms, Commented Nov 2, 2019 at 3:13

John M. · Accepted Answer · 2019-11-02 04:07:05Z

1

This is counter to the design of the SwiftUI framework. You should not have any persistent view around to call methods on. Instead, views are created and displayed as needed in response to your app's state changing.

For example, if your SceneDelegate had a reference to an instance of a model class, and your view depended on that model, you could modify the model in scene(_:continue:) and your view would update automatically.

If you can provide more specifics on what you're attempting to do, I may be able to give a more specific answer.

answered Nov 2, 2019 at 4:07

John M.

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Comments

Josen · Accepted Answer · 2019-11-03 13:04:39Z

Many thanks. Fully understood... Will read the docs...

So is this a possible way as an example:

class SceneDelegate: UIResponder, UIWindowSceneDelegate {

    var window: UIWindow?
    let activity = UserActivityManager()

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

        if let windowScene = scene as? UIWindowScene {
            let window = UIWindow(windowScene: windowScene)
            window.rootViewController = UIHostingController(rootView: contentView.environmentObject(activity))
            self.window = window
            window.makeKeyAndVisible()

            if let userActvity = connectionOptions.userActivities.first {
                guard let title = userActvity.title else { return }
                activity.doAction(action: title)
            }
        }
    }

    func scene(_ scene: UIScene, continue userActivity: NSUserActivity) {
        guard let title = userActivity.title else { return }
        activity.doAction(action: title)
    }
}

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