如何通过 Proxy 解决 Picker 选择问题？

Question

场景： 我想在通过选择器获取所选项目的同时处理选择事件。
这是参考 .

这就是我目前所拥有的。我无法将事件处理程序获取到 fire/activate/run doSomething().

import SwiftUI

struct ContentView: View {
    var body: some View {
        GeometryReader { _ in
            VStack {
                Text("PickerView")
                    .font(.headline)
                    .foregroundColor(.gray)
                    .padding(.top, 10)

                Picker("test", selection: Binding(get: { "" }, set: { _ in

                    doSomething()

                })) {
                    Text("Hello").id("1")
                    Text("Uncle").id("2")
                    Text("Ric").id("3")
                }.labelsHidden()

            }.background(RoundedRectangle(cornerRadius: 10)
                .foregroundColor(Color.white).shadow(radius: 1))
        }
        .padding()
    }

    func doSomething() {
        print("Hello Something!")
    }
}

注：我不知道如何处理 get{} 所以我在那里放了一个空字符串以满足编译器的要求。

我尝试评估闭包参数（通过 print(*closure parameter*)）但没有得到任何值，所以我放置了一个 _ 占位符以满足编译器的要求。

我如何收获选择？

闭包参数在这里似乎不起作用；因此占位符。没有多少例子可以遵循。

Answer 1

这是一个可能的解决方案：

struct ContentView: View {
    // extract picker values for easier access
    private let items = ["Hello", "Uncle", "Ric"]

    // store the currently selected value
    @State private var selection = 0

    // custom binding for the `selection`
    var binding: Binding<Int> {
        .init(get: {
            selection
        }, set: {
            selection = [=10=]
            doSomething() // call another function after the `selection` is set
        })
    }

    var body: some View {
        Picker("test", selection: binding) {
            ForEach(0 ..< items.count) { index in // use `ForEach` to quickly generate picker values
                Text(items[index])
                    .tag(index) // use `tag` instead of `id`
            }
        }
        .labelsHidden()
    }

    func doSomething() {
        print("Hello Something!")
    }
}

Answer 2

Discussion:

You can use onChange to trigger a side effect as the result of a value changing, such as an Environment key or a Binding...

(Apple doc.)

    struct ContentView: View {
    @State
    private var selection = 0
    let items = ["Hello", "Uncle", "Ric"]
    var body: some View {
        VStack {
            Picker("", selection: $selection) {
                ForEach(0..<items.count) {
                    Text(items[[=10=]])
                        .tag([=10=])
                }
            }
            .onChange(of: selection) { _ in
                print("Hello Something!")
            }
        }
    }
 }

如何通过 Proxy 解决 Picker 选择问题？

How do I resolve Picker selection via Proxy?

binding

picker

swiftui