在UIHostingController中从SwiftUI调用函数

Question

我有一个呈现SwiftUI的swift UIHostingController。我在视图中调用了一个函数，它构建得很好，但没有创建预期的输出。

class LoginView: UIHostingController<LoginViewComponent> {
    required init?(coder: NSCoder) {
        super.init(coder: coder, rootView: LoginViewComponent())
    }

    override func viewDidAppear(_ animated: Bool) {
        sessionHandler()
    }

    func sessionHandler(){
        let user = User()
        if user.isLoggedIn(){
            view.isUserInteractionEnabled = false
            print("Authenticating Session")
            self.rootView.loginState(state: "success")
        }else{
            view.isUserInteractionEnabled = true
            print("Needs Logging in")
        }
    }

}

当在SwiftUI视图类中调用时，函数("loginState(state："success")")可以工作，但是当从宿主控制器调用时，它就不能工作了。

任何帮助都将不胜感激。

Answer 1

实际上，SwiftUI是反应式的状态机，并且所有的视图都是结构值，所以你需要改变概念，而不是必须发送消息来指定状态依赖和对这些状态的反应……

因此，保持您的自定义主机控制器，它可以像下面这样设置

import SwiftUI
import UIKit
import Combine

// model that keeps login state
class LoginState: ObservableObject {
    @Published var state: String = ""
}

struct LoginViewComponent: View {
    @EnvironmentObject var loginState: LoginState // state to be observed

    ...
   // somewhere in body you use loginState.state
   // and view will be refreshed depending on state changes
}

class LoginView: UIHostingController<AnyView> {
    let loginState = LoginState() // here it is created

    required init?(coder: NSCoder) {
        super.init(coder: coder, rootView: AnyView(LoginViewComponent().environmentObject(self.loginState))) // here the ref injected
    }

    override func viewDidAppear(_ animated: Bool) {
        sessionHandler()
    }

    func sessionHandler(){
        let user = User()
        if user.isLoggedIn(){
            view.isUserInteractionEnabled = false
            print("Authenticating Session")
            self.loginState.state = "success" // here state changed
        }else{
            view.isUserInteractionEnabled = true
            print("Needs Logging in")
        }
    }

}