@Published 属性没有触发任何东西

Question

我有这个协议：

protocol MyProtocol:ObservableObject {
  var codeDetected:CodeDetected { get set }
  var codeDetectedPublished: Published<CodeDetected> { get }
  var codeDetectedPublisher: Published<CodeDetected>.Publisher { get }
}

这是检测到的代码

class CodeDetected:ObservableObject {
  var title: String
  var value:String

  init(title:String = "", value:String = ""){
    self.title = title
    self.value = value
  }
}

稍后上课...

class MyModel: MyProtocol {

  @Published var codeDetected:CodeDetected = CodeDetected()
  var codeDetectedPublished: Published<CodeDetected> { _codeDetected}
  var codeDetectedPublisher: Published<CodeDetected>.Publisher { $codeDetected }
}

问题是在这个类上改变codeDetected，并不会触发观察它的结构上的任何东西。

稍后实现

struct MyView: View {
  @ObservedObject let myModel = MyModel()

我正在为它设置新值

codeDetected = newCodeDetected

Answer 1

试着观察你的模型

@StateObject var myModel = MyModel()

没有Minimal Reproducible Example，我们将在这里分道扬镳。

您也没有观察title 和value。在他们身上贴上@Published，然后在他们自己的View中观察他们

protocol MyProtocol:ObservableObject {
    var codeDetected:CodeDetected { get set }
    //var codeDetectedPublished: Published<CodeDetected> { get }
    //var codeDetectedPublisher: Published<CodeDetected>.Publisher { get }
}

class CodeDetected:ObservableObject {
    @Published var title: String
    @Published var value:String
    
    init(title:String = "init", value:String = "init"){
        self.title = title
        self.value = value
    }
}
class MyModel: MyProtocol {
    
    @Published var codeDetected:CodeDetected = CodeDetected()
    //var codeDetectedPublished: Published<CodeDetected> { _codeDetected}
    //var codeDetectedPublisher: Published<CodeDetected>.Publisher { $codeDetected }
}
struct CodeDetectedView: View {
    @StateObject var myModel = MyModel()
    var body: some View {
        VStack{
            //Can't see updates here unless you ask for them/tell the parent model there are changes
            Text(myModel.codeDetected.title)
            .onReceive(myModel.codeDetected.$title, perform: { _ in
                myModel.objectWillChange.send()
            })
            Text(myModel.codeDetected.value)
                .onReceive(myModel.codeDetected.$value, perform: { _ in
                    myModel.objectWillChange.send()
                })
            CodeDetectedSubView(codeDetected: myModel.codeDetected)
        }
    }
}
struct CodeDetectedSubView: View {
    @ObservedObject var codeDetected: CodeDetected
    var body: some View {
        //Can see here
        Text(codeDetected.title)
        Text(codeDetected.value)
        TextField("title", text: $codeDetected.title)
        TextField("value", text: $codeDetected.value)
    }
}