在 SwiftUI 中的视图之间移动

Question

ok so, im on on SwiftUI Xcode 11.3.1 trying to call a second view after login

the working design of the second view is on the file mainView.swift

after the login I'm calling my view like this

Button(action: {
                self.status =  dologin(username: self.username, password: self.password)
                if (self.status){
                    print ("log in succesfull")
                    mainMenu() // <-- return of "mainMenu" initializer is unused

                }
            })

I know you can call a. subview like .sheet(isPresented) but this won't work for me cause is a login screen. thanks in advance.

Answer 1

You need to control views in other way in SwiftUI, you can't just push or pop view, like in UIKit. Apple proposes NavigationView and you can use something like NavigationLink(destination: YourLoginView(), isActive: $someBindingVariable, label: Text("")) , but I really don't like to play with .navigationBarHidden(true) and .navigationBarBackButtonHidden(true) and other staff. There are some options:

1. Use .popover(isPresented: $needToLogin) { // login view } . Either you can use .sheet . In this case user can move your "Login view" to bottom and use "Main view" as usual:

struct MovingViewsSwiftUI: View {

    @State private var needToLogin = true
    var body: some View {
        Rectangle() // your "Main view"
            .popover(isPresented: $needToLogin) {
                LoginView(needToLogin: self.$needToLogin) // will show you at the end
        }

    }

}

2. You can use if...else statements, for example:

//...
var body: some View {
    if needToLogin {
        return AnyView(LoginView)
    } else {
        return AnyView(MainView)
    }
    // something else in body
}

3. You can use ZStack and control views .opacity or .offset . It allows you to achieve interesting animations:

struct MovingViewsSwiftUI: View {

    @State private var needToLogin = true
    var body: some View {

        ZStack {
            LoginView(needToLogin: $needToLogin)
                .opacity(needToLogin ? 1 : 0)

            Rectangle()
                .opacity(needToLogin ? 0 : 1)

        }

    }

}

and here is the example of LoginView :

struct LoginView: View {

    @Binding var needToLogin: Bool
    @State private var email: String = ""
    @State private var password: String = ""

    var body: some View {
        VStack {
            TextField("enter email", text: $email)
            TextField("pass", text: $password)

            Button(action: {
                withAnimation {
                    self.needToLogin = false
                }

            }) {
                Text("Log in!")
            }
        }
        .padding()
    }
}

Answer 2

You can also add button in NaigationView like this.

 NavigationLink(destination: mainMenu()) {
                            Button(action: {

                            }) {
                              Text("Log in!")
                            }
                        }