ios - 为什么不更改 @ObservedObject 更新 UIViewRepresentable？

Question

我有一个简单的例子，我在父 View 中创建一个 @ObservedObject 并将其传递给子 UIViewRepresentable。当我单击“按钮”时，它会修改 @ObservableObject 但 subview 永远不会更新(即永远不会调用 updateUIView)。有没有其他方法可以做到这一点？

import SwiftUI

class UpdateViewState: ObservableObject {
  @Published var words = ["A", "B", "C"]

  func addWord(word: String) {
    print("added word")
    words.append(word)
  }
}

struct UpdateView: View {
  @ObservedObject private var state = UpdateViewState()

  var body: some View {
    VStack {
      UpdateViewRepresentable(state: state)
      Text("Button").onTapGesture {
        self.state.addWord(word: "A")
      }
    }
  }
}

struct UpdateViewRepresentable: UIViewRepresentable {
  @ObservedObject var state: UpdateViewState

  func makeUIView(context: Context) -> UILabel {
    let view = UILabel()
    view.text = "Hello World"
    return view
  }

  func updateUIView(_ uiView: UILabel, context: UIViewRepresentableContext<UpdateViewRepresentable>) {
    print("updateUIView")
    uiView.text = state.words.joined(separator: ", ")
  }
}

Answer 1

试试这个:

public final class UpdateViewState: ObservableObject {

  @Published var words = ["A", "B", "C"]

  func addWord(word: String) {
    print("added word ", words)
    words.append(word)
  }
}

struct ContentView: View {

 @EnvironmentObject private var state: UpdateViewState

  var body: some View {
    VStack {
        UpdateViewRepresentable(state: .constant(state))
      Text("Button").onTapGesture {
        self.state.addWord(word: "A")
      }
    }.onAppear() {
        self.state.words.append("aha")
    }
  }
}

struct UpdateViewRepresentable: UIViewRepresentable {

    @Binding var state: UpdateViewState

  func makeUIView(context: Context) -> UILabel {
    let view = UILabel()
    view.text = "Hello World"
    return view
  }

  func updateUIView(_ uiView: UILabel, context: UIViewRepresentableContext<UpdateViewRepresentable>) {
    print("updateUIView")
    uiView.text = state.words.joined(separator: ", ")
  }
}