如何在SwiftUI应用程序中返回登录视图

import SwiftUI

struct MainView: View {
    @State private var isLoggedIn = false
    
    var body: some View {
        if isLoggedIn {
            // 显示主要内容视图
            Text("Welcome to the app!")
        } else {
            // 显示登录视图
            LoginView(isLoggedIn: $isLoggedIn)
        }
    }
}

struct LoginView: View {
    @Binding var isLoggedIn: Bool
    @Environment(\.presentationMode) var presentationMode
    
    var body: some View {
        VStack {
            // 输入字段
            TextField("Username", text: .constant(""))
                .textFieldStyle(RoundedBorderTextFieldStyle())
                .padding()
            
            TextField("Password", text: .constant(""))
                .textFieldStyle(RoundedBorderTextFieldStyle())
                .padding()
            
            // 登录按钮
            Button(action: {
                // 模拟登录成功
                isLoggedIn = true
                // 返回主视图
                presentationMode.wrappedValue.dismiss()
            }) {
                Text("Login")
                    .padding()
                    .foregroundColor(.white)
                    .background(Color.blue)
                    .cornerRadius(10)
            }
        }
        .padding()
    }
}