SwiftUI NavigationLink: Navigate to a destination view AFTER running account creation code successfully

Question

I want to run account creation logic and then, if successful, transition to the destination view. Otherwise, I'll present an error sheet. NavigationLink transitions immediately to the destination view on tap.

I can get it to work if I create a phantom NavigationLink using the isActive overload and an empty string as the text (which creates a view with a zero frame). Then I toggle the isActive property with a Button presented to the user that runs the account creation logic first and at the end of the chain toggles the NavigationLink to active. I am inside a NavigationView.

        @State private var isActive: Bool = false

        NavigationView {

            // Name, Email, Password Textfields here

            // Button to run account creation logic:

            Button(action: {
                // Account creation promise chain here, then...
                self.isActive.toggle()
            }) {
                Text("Create Account")
            }

            // Phantom navigation link:

            NavigationLink("", destination: VerifyEmailView(email: email), isActive: self.$isActive)

        }

Is there a better way to do this? It seems bad practice to trigger running the account creation logic from a button, and then activate a phantom navigation link to transition to the next screen.

Answer 1

There is a very simple approach to handle your views' states and NavigationLinks. You can notify your NavigationLink to execute itself by binding a tag to it. You can then set-unset the tag and take control of your NavigationLink.

struct SwiftView: View {
@State private var actionState: Int? = 0

var body: some View {

    NavigationView {
                VStack {
                    NavigationLink(destination: Text("Destination View"), tag: 1, selection: $actionState) {
                        EmptyView()
                    }


                    Text("Create Account")
                        .onTapGesture {
                            self.asyncTask()
                    }
                }
            }
    }

func asyncTask() {
    //some task which on completion will set the value of actionState
    self.actionState = 1
}

}

Here we have binded the actionState with our NavigationLink, hence whenever the value of actionState changes, it will be compared with the tag associated with our NavigationLink.

Your Destination View will not be visible until you set the value of actionState equal to the tag associated with our NavigationLink.

Like this you can create any number of NavigationLinks and can control them by changing just one Bindable property.

Thanks, hope this helps.

Answer 2

Building off of Mohit's answer, making a little more Swifty with an enum that encapsulates screen state:

enum ActionState: Int {
    case setup = 0
    case readyForPush = 1
}

struct SwiftView: View {
    @State private var actionState: ActionState? = .setup

    var body: some View {

        NavigationView {
                VStack {
                    NavigationLink(destination: SomeView, tag: .readyForPush, selection: $actionState) {
                        EmptyView()
                    }


                    Text("Create Account")
                        .onTapGesture {
                            self.asyncTask()
                    }
                }
            }
       }

func asyncTask() {
    //some task which on completion will set the value of actionState
    self.actionState = .readyForPush
}

Answer 3

You can wrap your Destination View in a lazy view to prevent the immediate invocation. Here's an example:

struct LazyView<Content: View>: View {
    let build: () -> Content
    init(_ build: @autoclosure @escaping () -> Content) {
        self.build = build
    }
    var body: Content {
        build()
    }
}

Eventually, invoke it like this:

NavigationLink(destination: LazyView(Text("Detail Screen"))){//your code}

I've written a full blog post covering this a few other pitfalls of NavigationLinks in SwiftUI. Refer here.