SwiftUI Picker选择更改时，有没有一种方法可以调用函数？

Z时代
2024-01-10
分类：问答

当selectedOption的值更改时，我想调用一个函数。在SwiftUI中，有没有一种类似于编辑TextField的方法？

具体来说，我想在用户更改selectedOption时保存选择的选项。

这是我的选择器：

struct BuilderPicker: View {
    let name: String
    let options: Array<String>
    @State var selectedOption = 0
    var body: some View {
        HStack {
            Text(name)
                .font(.body)
                .padding(.leading, 10)
            Picker(selection: $selectedOption, label: Text(name)) {
                ForEach(0 ..< options.count) {
                    Text(self.options[$0]).tag($0)
                }
            }.pickerStyle(SegmentedPickerStyle())
                .padding(.trailing, 25)
        }.onTapGesture {
            self.selectedOption = self.selectedOption == 0 ? 1 : 0
        }
            .padding(.init(top: 10, leading: 10, bottom: 10, trailing: 0))
            .border(Color.secondary, width: 3)
            .padding(.init(top: 0, leading: 15, bottom: 0, trailing: 15))
            .font(.body)
    }
}

我仍然是SwiftUI的新手，希望获得一些帮助。谢谢！

回答：

如果在视图中使用@State值，则不需要多余的变量 name

  struct BuilderPicker: View {
// let name: String = ""
 let options: Array<String> = ["1", "2","3","4","5"]
 @State var selectedOption = 0
 var body: some View {
    HStack {
        Text(options[selectedOption])
            .font(.body)
            .padding(.leading, 10)
        Picker(selection: $selectedOption, label:    Text(options[selectedOption])) {
            ForEach(0 ..< options.count) {
                Text(self.options[$0]).tag($0)
            }
        }.pickerStyle(SegmentedPickerStyle())
            .padding(.trailing, 25)}
//        }.onTapGesture {
//            self.selectedOption = self.selectedOption == 0 ? 1 : 0
//        }
        .padding(.init(top: 10, leading: 10, bottom: 10, trailing: 0))
        .border(Color.secondary, width: 3)
        .padding(.init(top: 0, leading: 15, bottom: 0, trailing: 15))
        .font(.body)
    }
 }

如果需要对@State进行单独的操作，最简单的方法是在视图中添加一行：onReceive（）。

  HStack {
        Text("")
            .font(.body)
            .padding(.leading, 10)
        Picker(selection: $selectedOption, label: Text("")) {
            ForEach(0 ..< options.count) {
                Text(self.options[$0]).tag($0)
            }
        }.pickerStyle(SegmentedPickerStyle())
            .padding(.trailing, 25)}
  //        }.onTapGesture {
 //            self.selectedOption = self.selectedOption == 0 ? 1 : 0
 //        }
        .padding(.init(top: 10, leading: 10, bottom: 10, trailing: 0))
        .border(Color.secondary, width: 3)
        .padding(.init(top: 0, leading: 15, bottom: 0, trailing: 15))
        .font(.body)
        .onReceive([self.selectedOption].publisher.first()) { (value) in
            print(value)
    }