如何return查看编辑其属性？

Question

我正在制作 class 其编辑器视图 returns。但是报错

Cannot convert value of type 'Published.Publisher' to expected argument type 'Binding'

这是 Playgrounds 的简单测试代码。

import SwiftUI
import PlaygroundSupport


struct EditorView: View {
    @Binding var text: String

    var body: some View {
        HStack {
            Text("Name:")
            TextField("Jerry", text: $text)
        }
    }
}

class MyModel: ObservableObject {
    @Published var name: String = "Tom"

    func editorView() -> some View {
        EditorView(text: $name) // [ERROR] Cannot convert value of type 'Published.Publisher' to expected argument type 'Binding<String>'
    }
}

struct ContentView: View {
    @StateObject var model: MyModel = .init()

    var body: some View {
        model.editorView()
    }
}

struct ContentView_Preview: PreviewProvider {
    static var previews: some View {
        ContentView()
            .previewLayout(.fixed(width: 375, height: 400))
    }
}

let viewController = UIHostingController(rootView: ContentView())
let nav = UINavigationController(rootViewController: viewController)
PlaygroundPage.current.liveView = nav

怎么了？

2022.03.23 添加

我测试了不绑定的视图，可以。我认为 class 可以用它的属性创建一个视图。但是不能通过@Binding.

import SwiftUI
import PlaygroundSupport


struct EditorView: View {
    @Binding var text: String

    var body: some View {
        HStack {
            Text("Name:")
            TextField("Jerry", text: $text)
        }
    }
}

// Just display the name parameter
struct DispView: View {
    let name: String
    var body: some View {
        Text(name)
    }
}

class MyModel: ObservableObject {
    @Published var name: String = "Tom"

    @ViewBuilder
    func editorView() -> some View {
//      EditorView(text: $name) // Error at this line.
        DispView(name: name) // Pass the property.
    }
}

struct ContentView: View {
    @StateObject var model: MyModel = .init()

    var body: some View {
        model.editorView()
    }
}

struct ContentView_Preview: PreviewProvider {
    static var previews: some View {
        ContentView()
            .previewLayout(.fixed(width: 375, height: 400))
    }
}

let viewController = UIHostingController(rootView: ContentView())
let nav = UINavigationController(rootViewController: viewController)
PlaygroundPage.current.liveView = nav

Answer 1

绑定由 StateObject 包装器（在 ObservableObject 上）提供，视图应在 body 中创建（即在视图层次结构中），因此它应该看起来像

struct ContentView: View {
    @StateObject var model: MyModel = .init()

    var body: some View {
        EditorView(text: model.$name)     // << here !!
    }
}

注意： 替代方法是让 EditorView 直接依赖于 MyModel，然后在这样的视图中你可以创建一个包装器来提供所需的绑定.

Answer 2

您在错误的位置创建了 EditorView，将它放在您的 ContentView 而不是您的 ViewModel 中。 ViewModel 用于保存数据（或模型）而不是 View。我认为 SwiftUI 不是为携带视图而设计的。

struct ContentView: View {
    @StateObject var model: MyModel = .init()

    var body: some View {
        editorView
    }
}

extension ContentView {
    @ViewBuilder
    var editorView: some View {
        EditorView(text: $model.name)
    }
}

如果您仍想将它放在您的 ViewModel 中，这应该是工作代码。您可以创建新的绑定作为视图初始化程序的参数。

@ViewBuilder
func editorView() -> some View {
    EditorView(text: 
        Binding { name } set: { newName in self.name = newName }
    )
}

如何return查看编辑其属性？

How to return View for editing its property?

ios

swift

swiftui