swift - 从 View 模型中关闭 View [MODAL PAGE]

Question

我正在使用 swiftUI 并结合，我的虚拟机中有一些业务逻辑。有些结果不得不否定我的观点。

我在某些 View 中使用了这个:

@Environment(\.presentationMode) var presentationMode: Binding<PresentationMode>

self.presentationMode.wrappedValue.dismiss()

我想在我的 View 模型中使用类似的东西。

Answer 1

您不会在 SwiftUI 中以命令式的方式进行解雇。 .相反，您使用 .sheet通过将其绑定(bind)到将从该 View 模型中变异的 bool 属性来查看 View 。

编辑:

After answering a follow-up question, I came up with a different approach. It plays nice if the dismissal is actually needed to be done from inside the modally presented View itself.

您可以通过实现自定义 Publisher 来实现此目的。将使用 .send()允许您向订阅者发送特定值的方法(在本例中为您的 View )。您将使用 onReceive(_:perform:) View 上定义的方法 的协议(protocol)SwiftUI 订阅自定义 Publisher的输出流你定义的。里面 perform操作关闭，您将可以访问发布者的最新发出值，您将实际解雇您的 View .

理论说的够多了，可以看代码，应该不难理解，如下:

import Foundation
import Combine

class ViewModel: ObservableObject {
    var viewDismissalModePublisher = PassthroughSubject<Bool, Never>()
    private var shouldDismissView = false {
        didSet {
            viewDismissalModePublisher.send(shouldDismissView)
        }
    }

    func performBusinessLogic() {
        DispatchQueue.main.asyncAfter(deadline: .now() + 2) {
            self.shouldDismissView = true
        }
    }
}

和意见同行是:

import SwiftUI

struct ContentView: View {
    @State private var isDetailShown = false
    var body: some View {
        VStack {
            Text("Hello, World!")
            Button(action: {
                self.isDetailShown.toggle()
            }) {
                Text("Present Detail")
            }
        }
        .sheet(isPresented: $isDetailShown) {
            DetailView()
        }
    }
}

struct DetailView: View {
    @ObservedObject var viewModel = ViewModel()
    @Environment(\.presentationMode) private var presentationMode
    var body: some View {
        Text("Detail")
        .navigationBarTitle("Detail", displayMode: .inline)
        .onAppear {
            self.viewModel.performBusinessLogic()
        }
        .onReceive(viewModel.viewDismissalModePublisher) { shouldDismiss in
            if shouldDismiss {
                self.presentationMode.wrappedValue.dismiss()
            }
        }
    }
}

老答案:

关于 View 模型中业务逻辑更改的 View 解除的一个非常简单的实现是:

struct ContentView: View {
    @ObservedObject var viewModel = ViewModel()
    var body: some View {
        Text("Hello, World!")

        // the animation() modifier is optional here
        .sheet(isPresented: $viewModel.isSheetShown.animation()) { 
            Text("Sheet Presented")
        }

        // From here - for illustration purpose
        .onAppear {
            self.viewModel.perform()
        }
        // To here

    }
}

class ViewModel: ObservableObject {
    @Published var isSheetShown = false

    func perform() {
        // this just an example. In real application, you will be responsible to
        // toggle between the states of the `Bool` property
        DispatchQueue.main.asyncAfter(deadline: .now() + 2) {
            self.isSheetShown.toggle()
            DispatchQueue.main.asyncAfter(deadline: .now() + 2) {
                self.isSheetShown.toggle()
            }
        }
    }
}