Trying to access the environment object created inside scene delegate by another scenedelegate function

Question

I have created an environment object in my scendelegate and want to also use it in another function that resides inside my scenedelegate. The code looks as follows:

SceneDelegate.swift

    class SceneDelegate: UIResponder, UIWindowSceneDelegate {
    
        var window: UIWindow?
        //@EnvironmentObject var data: DataFetcher
        var data = DataFetcher()
    
        func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
 
            if let windowScene = scene as? UIWindowScene {
                
                let window = UIWindow(windowScene: windowScene)
                let data = (UIApplication.shared.delegate as! AppDelegate).self.data
                window.rootViewController = UIHostingController(rootView: ContentView().environmentObject(data))
                self.window = window
                window.makeKeyAndVisible()
            }
        }
        
        func handleIncomingDynamicLink(_ dynamicLink: DynamicLink){
            guard let url = dynamicLink.url else {
                print("That's weird. My dynamic link object has no url")
                return
            }
            print("Your incoming link parameter is \(url.absoluteString)")
            guard let components = URLComponents(url: url, resolvingAgainstBaseURL: false),
                let queryItems = components.queryItems else {return}
            self.data.linkRecieved = true
            print(data.linkRecieved)
        }
func scene(_ scene: UIScene, continue userActivity: NSUserActivity) {
        if let incomingURL = userActivity.webpageURL {
            print("Incoming URL is \(incomingURL)")
            _ = DynamicLinks.dynamicLinks().handleUniversalLink(incomingURL) { (dynamicLink, error) in
                guard error == nil else{
                    print("Found an error! \(error!.localizedDescription)")
                    return
                }
                if let dynamicLink = dynamicLink {
                    self.handleIncomingDynamicLink(dynamicLink)
                }
            }
        }
    }
        

The problem is that the environment object's linkRecieved variable is not changed inside contentview when the handleIncomingDynamicLink function is executed (I have verified the variable is indeed changed to true once the function is run). Any insight in fixing this issue is much appreciated!!!

Answer 1

You have assigned a DataFetcher instance to the data property, presumably to set its type and eliminate the error that your property isn't initialised.

Then in willConnectTo you get the DataFetcher instance from your AppDelegate. Your dataproperty and the localdatavariable inwillConnectTo(That you subsequently add to the environment) now reference different instances ofDataFetcher`, but you didn't realise.

I am not a big fan of assigning "throw away" instances to properties for this reason.

A better approach is to use an implicitly unwrapped optional. That way if you don't assign a value to the property you will get a crash and quickly work out that something isn't right.

Then in willConectTo you can assign the instance from your AppDelegate to the property and put it in the environment.

class SceneDelegate: UIResponder, UIWindowSceneDelegate {
    
        var window: UIWindow?
        //@EnvironmentObject var data: DataFetcher
        var data: DataFetcher!
    
        func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
 
            if let windowScene = scene as? UIWindowScene {
                
                let window = UIWindow(windowScene: windowScene)
                self.data = (UIApplication.shared.delegate as! AppDelegate).self.data
                window.rootViewController = UIHostingController(rootView: ContentView().environmentObject(data))
                self.window = window
                window.makeKeyAndVisible()
            }
        }

Answer 2

You need to inject that var data which is property, so remove the following line

let window = UIWindow(windowScene: windowScene)
//let data = (UIApplication.shared.delegate as! AppDelegate).self.data // << this one
window.rootViewController = UIHostingController(rootView: 
   ContentView().environmentObject(self.data))   // << inject own property