SwiftUI 认证视图 [英] SwiftUI authentication view

问题描述

在 swift UI 中，我希望内容视图成为我的应用程序的根视图，并带有条件设置以检查用户是否已登录.如果用户登录列表视图，则显示其他明智的登录视图，以便用户可以登录.根据我的研究，我找不到最好的方法来做到这一点.

In swift UI I want the content view to be my root view for my app with a conditional setup to check if the users is logged in or not. If the user is logged in a list view shows other wise show the login view so the user can log in. Based on my research i could not find a best way to do this.

在我的情况下，我无法找到可行的解决方案，也不知道它是否是最佳解决方案.

In my case I can not get the solution I found to work and do not know if it is the best solution.

import SwiftUI

struct ContentView: View {
    @ObservedObject var userAuth: UserAuth = UserAuth()
    // MARK: - View

    @ViewBuilder
    var body: some View {
        if !userAuth.isLoggedin {
            return LoginView().environmentObject(userAuth)
        } 
        return  BookList()
    }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}

import Combine

class UserAuth: ObservableObject {

    let didChange = PassthroughSubject<UserAuth,Never>()

    // required to conform to protocol 'ObservableObject'
    let willChange = PassthroughSubject<UserAuth,Never>()

    func login() {
        // login request... on success:
        self.isLoggedin = true
    }

    func logout() {
        // login request... on success:
        self.isLoggedin = false
    }

    var isLoggedin = false {
        didSet {
            didChange.send(self)
        }

//        willSet {
//            willChange.send(self)
//        }
    }
}

运行时，我得到的只是一个白屏.似乎视图构建器可能是问题所在，但删除了我在内容视图上出现不透明错误

When running this all i get is a white screen. It seems that the view builder might be the problem but removing that i get a opaque error on content view

推荐答案

提供的代码快照有两个问题:1) 视图构建器内容不正确，以及 2) 模型不正确.

There two problems with provided code snapshot: 1) incorrect view builder content, and 2) incorrect model.

见下文，两者均已修复.使用 Xcode 11.4/iOS 13.4 测试

See below both fixed. Tested with Xcode 11.4 / iOS 13.4

struct ContentView: View {
    @ObservedObject var userAuth: UserAuth = UserAuth()
    // MARK: - View

    @ViewBuilder              // no need return inside
    var body: some View {
        if !userAuth.isLoggedin {
            LoginView().environmentObject(userAuth)
        }
        else {
            BookList()
        }
    }
}

import Combine

class UserAuth: ObservableObject {
    @Published var isLoggedin = false     // published property to update view

    func login() {
        // login request... on success:
        self.isLoggedin = true
    }

    func logout() {
        // login request... on success:
        self.isLoggedin = false
    }
}

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