如何在 SwiftUI 中从登录视图转换为 tabView [英] How do I transition from a login view to a tabView in SwiftUI

问题描述

我有一个 Google 登录屏幕，然后它应该会转换为 TabView.我尝试使用 ZStack，但它导致应用程序在加载每个选项卡之前出现故障.它将显示登录按钮一秒钟，然后会出现正确的选项卡.

I have a Google Sign-in screen, and then it should transition to a TabView. I tried using a ZStack, but it's causing the app to glitch before each tab is loaded. It will show the sign-in button for a second, and then the correct tab will appear.

有没有办法完全类似于 ViewControllers?或者有没有办法在我调用新视图 (MainView) 之前完全删除登录按钮?

Is there a way to totally segue similar to ViewControllers? Or is there a way to totally remove the sign-in button before I call the new view (MainView)?

MainView 只是一个带有 tabView 和 tabItems 的 SwiftUI 视图.

MainView is just a SwiftUI view with a tabView, and tabItems.

我有一个 SwiftUI SignInView:

I have a SwiftUI SignInView:

import SwiftUI
import GoogleSignIn

struct SignInView: View {

    @State var loggedIn = false

    let logo = Image('googleLogo')


    var body: some View {
        ZStack {
            Button(action: {
                self.signIn {
                    self.loggedIn = true
                }

            }, label: {
                VStack {
                    logo
                        .padding(EdgeInsets(top: 8, leading: 16, bottom: 8, trailing: 16))
                        .background(Color.white)
                        .cornerRadius(8.0)
                        .shadow(radius: 4.0)
                     Text("Sign-In")
                        .foregroundColor(.primary)
                        .multilineTextAlignment(.center)
                        .padding(5)
                }
            }).zIndex(-1)
            if loggedIn {
                MainView()
            }
        }
    }
    func signIn(completion: @escaping () -> Void) {
           GIDSignIn.sharedInstance()?.presentingViewController = UIApplication.shared.windows.last?.rootViewController
           GIDSignIn.sharedInstance()?.signIn()
           DispatchQueue(label: "SignIn Check", qos: DispatchQoS.background).async(execute: { () -> Void in
               while true {
                   if GIDSignIn.sharedInstance()?.currentUser != nil {
                       completion()
                       break
                   }
               }

           })

       }
    }

    struct SignInView_Previews: PreviewProvider {
        static var previews: some View {
          SignInView()
        }
    }

推荐答案

您可以保持 ZStack 的原样，并使登录按钮成为条件的一部分，以解决您看到的小故障，但更简洁的解决方案是使用 Group 而不是 ZStack ，其中包含登录条件:

You can keep your ZStack the way it is and make the sign in button a part of the conditional too in order to fix the glitching you're seeing, but a cleaner solution would be to use a Group instead of a ZStack with the login conditional inside of it:

var body: some View {
    Group {
        if !loggedIn {
            Button(action: {
                self.signIn {
                    self.loggedIn = true
                }

            }, label: {
                VStack {
                    logo
                        .padding(EdgeInsets(top: 8, leading: 16, bottom: 8, trailing: 16))
                        .background(Color.white)
                        .cornerRadius(8.0)
                        .shadow(radius: 4.0)
                    Text("Sign-In")
                        .foregroundColor(.primary)
                        .multilineTextAlignment(.center)
                        .padding(5)
                }
            })
        } else {
            MainView()
        }
    }
}

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