当涉及协调器时，如何在 SwiftUI 视图与另一个视图之间进行通信? [英] How do I communicate between a SwiftUI view to another when a coordinator is involved?

问题描述

我是 SwiftUI 的新手.刚学几天.我试图找到有关此的教程，但没有成功.

I am new to SwiftUI. Just a few days trying to learn. I have tried to find a tutorial on this but I was not successfull.

假设我有以下观点:

Struct MyPicker: View {

MyPicker 位于 ContentView 内的 VStack 内.我必须从 MyPicker 到 ContentView 传递 3 个参数:color、width 和 type.

MyPicker is inside a VStack inside ContentView. I have to pass, from MyPicker to ContentView, 3 parameters: color, width and type.

问题是这些值来自 MyPicker 内的委托回调.所以我必须在 MyPicker 里面有一个协调器.

The problem is that these values come from a delegate callback inside MyPicker. So I have to have a coordinator inside MyPicker.

struct MyPickerHelper: UIViewRepresentable {
  class Coordinator:NSObject, MyPickerDelegate {
    var color:UIColor
    var width:CGFloat
    var type:PKInkingTool.InkType 

    func toolPickerSelectedToolDidChange(_ toolPicker: PKToolPicker) {
      if toolPicker.selectedTool is PKInkingTool {
        let tool = toolPicker.selectedTool as! PKInkingTool
        self.color = tool.color
        self.width = tool.width
        self.type = tool.inkType
      }
    }

有很多东西，比如@Binding、@Published、@State 等等.我该放什么来制作MyPicker传达对 ContentView 的更改?

Theare are a lot of stuff like @Binding, @Published, @State, etc. What do I put where to make MyPicker communicate changes to ContentView?

推荐答案

您需要将状态作为父视图中的真实来源，并将绑定传递给可表示视图，这...这里是一个参数的示例...

You need to have state as source of truth in parent view and pass binding to it into representable view, which... here is an example for one parameter...

struct MyPicker: View {
   @State private var color: UIColor = .clear   // << source

   var body: some View {
      MyPickerHelper(color: $color)     // << pass binding
   }
}

现在可以表示

struct MyPickerHelper: UIViewRepresentable {
  @Binding var color: UIColor

  func makeCoordinator() -> Coordinator {
     Coordinator(owner: self)
  }

  ...

  class Coordinator:NSObject, MyPickerDelegate {
    private var owner: MyPickerHelper

    init(owner: MyPickerHelper) {
      self.owner = owner
    }

    func toolPickerSelectedToolDidChange(_ toolPicker: PKToolPicker) {
      if toolPicker.selectedTool is PKInkingTool {
        let tool = toolPicker.selectedTool as! PKInkingTool

        self.owner.color = tool.color         // << here update via binding !!!
      }
    }

   ...
}

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