SwiftUI:ViewModifier不侦听onReceive事件 [英] SwiftUI: ViewModifier doesn't listen to onReceive events

问题描述

我有一个自定义的 ViewModifier ，它仅返回与 onReceive 修饰符关联的相同内容，不会触发 onReceive ，这是一个您可以复制，粘贴并在 XCode 中运行的示例代码:

I have a custom ViewModifier which simply returns the same content attached with a onReceive modifier, the onReceive is not triggered, here is a sample code that you can copy, paste and run in XCode:

import SwiftUI
import Combine

class MyViewModel: ObservableObject {
    @Published var myProperty: Bool = false
}
struct ContentView: View {
    @ObservedObject var viewModel: MyViewModel

    var body: some View {
        Text("Hello, World!")
        .modifier(MyOnReceive(viewModel: viewModel))
            .onTapGesture {
                self.viewModel.myProperty = true
        }
    }
}

struct MyOnReceive: ViewModifier {
    @ObservedObject var viewModel: MyViewModel

    func body(content: Content) -> some View {
        content
            .onReceive(viewModel.$myProperty) { theValue in
                print("The Value is \(theValue)") // <--- this is not executed
        }
    }
}

是 SwiftUI 旨在禁止 onReceive 在 ViewModifier 内部执行还是错误?我在现实生活中的项目中有了一个视图，该视图变得更大了，并且在 onReceive 中放入了一些业务逻辑，因此我需要通过将视图与 onReceive 分开来清理该视图.

is SwiftUI designed to disallow onReceive to execute inside a ViewModifier or is it a bug ? I have a view in my real life project that gets bigger with some business logic put inside onReceive, so I need to clean that view by separating it from onReceive.

推荐答案

好的，这对我有用:

func body(content: Content) -> some View {
    content
        .onAppear()   // <--- this makes it work
        .onReceive(viewModel.$myProperty) { theValue in
            print("-----> The Value is \(theValue)") // <--- this will be executed
    }
}

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