从选择器 SwiftUI 中取消选择项目

问题描述

我使用带有选择器的表单，一切正常(我可以从选择器中选择一个元素)，但我无法取消选择它.是否存在从选择器中取消选择项目的方法?谢谢！

Picker(selection: $model.countries, label: Text("country")) {ForEach(model.countries, id: \.self) { country in文本(国家！.名称).tag(国家)}}

解决方案

首先，我们可以修复选择.它应该与标签的类型相匹配.标签被赋予 Country，所以要选择一个什么都不选的选项，我们应该使用 Country? 作为 selection 类型.>

它应该是这样的:

struct ContentView: 查看 {@ObservedObject 私有变量模型 = Model()@State 私有变量选择:国家?var主体:一些视图{导航视图{形式 {Picker(selection: $selection, label: Text("country")) {ForEach(model.countries, id: \.self) { country in文本(国家！.名称).tag(国家)}}按钮(清除"){选择 = 无}}}}}

然后您只需要将selection 设置为nil，这在按钮中完成.您可以通过任何您想要的操作将 selection 设置为 nil.

I use a form with a picker, and everything works fine (I am able to select an element from the picker), but I cannot deselect it. Does there exist a way to deselect an item from the picker?Thank you!

Picker(selection: $model.countries, label: Text("country")) {
                        ForEach(model.countries, id: \.self) { country in
                            Text(country!.name)
                                .tag(country)
                        }
                    }

解决方案

First of, we can fix the selection. It should match the type of the tag. The tag is given Country, so to have a selection where nothing might be selected, we should use Country? as the selection type.

It should looks like this:

struct ContentView: View {

    @ObservedObject private var model = Model()
    @State private var selection: Country?

    var body: some View {
        NavigationView {
            Form {
                Picker(selection: $selection, label: Text("country")) {
                    ForEach(model.countries, id: \.self) { country in
                        Text(country!.name)
                            .tag(country)
                    }
                }

                Button("Clear") {
                    selection = nil
                }
            }
        }
    }
}

You then just need to set the selection to nil, which is done in the button. You could set selection to nil by any action you want.

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