SwiftUI用按钮更改视图

Question

我了解有PresentationButton和NavigationButton以便在最新的SwiftUI中更改视图。但是我想做一个简单的操作，如下所示。如果凭据正确，则用户单击“登录”按钮时，它将登录它们，但也会进行登录（在这种情况下，请更改视图）。但是，我无法在PresentationButton中检查它们是否正确，也无法在普通按钮中更改视图。还有另一种方法吗？

  @IBAction func signInClicked(_ sender: Any) {

        if emailText.text != "" && passwordText.text != "" {

            Auth.auth().signIn(withEmail: emailText.text!, password: passwordText.text!) { (userdata, error) in
                if error != nil {
                   //error
                } else {

                   performSegue(withIdentifier: "toFeedActivity", sender: nil)


                }
            }

        } else {
            //error
        }




    }

Answer 1

这是一种方法。

struct AppContentView: View {

    @State var signInSuccess = false

    var body: some View {
        return Group {
            if signInSuccess {
                AppHome()
            }
            else {
                LoginFormView(signInSuccess: $signInSuccess)
            }
        }
    }
}

struct LoginFormView : View {

    @State private var userName: String = ""
    @State private var password: String = ""

    @State private var showError = false

    @Binding var signInSuccess: Bool

    var body: some View {
        VStack {
            HStack {
                Text("User name")
                TextField($userName, placeholder: Text("type here"))
            }.padding()

            HStack {
                Text(" Password")
                TextField($password, placeholder: Text("type here"))
                    .textContentType(.password)
            }.padding()

            Button(action: {
                // Your auth logic
                if(self.userName == self.password) {
                    self.signInSuccess = true
                }
                else {
                    self.showError = true
                }

            }) {
                Text("Sign in")
            }

            if showError {
                Text("Incorrect username/password").foregroundColor(Color.red)
            }
        }
    }
}

struct AppHome: View {

    var body: some View {
        VStack {
        Text("Hello freaky world!")
        Text("You are signed in.")
        }
    }
}

Answer 2

我在我的一个应用程序中有同样的需求，我找到了一个解决方案......

基本上你需要在 NavigationView 中插入你的主视图，然后在你的视图中添加一个不可见的 NavigationLink，创建一个 @state var 来控制你何时想要推送视图并在你的登录回调中更改它的值......

那是代码：

struct ContentView: View {
    @State var showView = false
    var body: some View {
        NavigationView {
            VStack {
                Button(action: {
                    print("*** Login in progress... ***")
                    DispatchQueue.main.asyncAfter(deadline: .now() + 3) {
                        self.showView = true
                    }
                }) {
                    Text("Push me and go on")
                }

                //MARK: - NAVIGATION LINKS
                NavigationLink(destination: PushedView(), isActive: $showView) {
                    EmptyView()
                }
            }
        }
    }
}


struct PushedView: View {
    var body: some View {
        Text("This is your pushed view...")
            .font(.largeTitle)
            .fontWeight(.heavy)
    }
}