在SwiftUI中继承ObservableObject时不触发视图刷新 [英] View refreshing not triggered when ObservableObject is inherited in SwiftUI

问题描述

ContentView2视图，如果Model直接符合ObservableObject而不是继承SuperModel，那么它将正常工作

ContentView2 view is not refreshed when model.value changes, if Model conforms to ObservableObject directly instead of inheriting SuperModel then it works fine

class SuperModel: ObservableObject {

}

class Model: SuperModel {
    @Published var value = ""
}

struct ContentView2: View {

    @ObservedObject var model = Model()

    var body: some View {
        VStack {
            Text(model.value)
            Button("change value") {
                self.model.value = "\(Int.random(in: 1...10))"
            }
        }

    }
}

推荐答案

这是您示例的有效变体.请注意，要使其能够正常工作，不仅需要链接发布者，而且至少需要链接一个Publisher属性.大约在某种情况下它可能会有所帮助.

Here is working variant of your example. See that to be able to work, not only chaining the publishers is required, but at least one Published property. So or so, it could help in some scenario.

import SwiftUI

class SuperModel: ObservableObject {
    // this is workaround but not real trouble.
    // without any value in supermodel there is no real usage of SuperModel at all
    @Published var superFlag = false
}

class Model: SuperModel {
    @Published var value = ""
    override init() {
        super.init()
        _ = self.objectWillChange.append(super.objectWillChange)
    }
}

struct ContentView: View {

    @ObservedObject var model = Model()

    var body: some View {
        VStack {
            Text(model.value)
            Button("change value") {
                self.model.value = "\(Int.random(in: 1...10))"
            }
        }

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

将代码更改为

var body: some View {
        VStack {
            Text(model.value)
            Button("change value") {
                self.model.value = "\(Int.random(in: 1...10))"
            }
            Text(model.superFlag.description)
            Button("change super flag") {
                self.model.superFlag.toggle()
            }
        }

    }

您可以看到如何同时使用超级模型

you can see how to use even your supermodel at the same time

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