通过 Picker 更改 @Published var [英] Change a @Published var via Picker

问题描述

我想通过 Picker 更改 @Published var，但我发现它无法编译.

I would like to change a @Published var through the Picker but I found that it fails to compile.

我有一个语言结构:

enum Language: Int, CaseIterable, Identifiable, Hashable {
case en
case zh_hant

var description: String {
    switch self {
    case.en:
        return "English"
    case.zh_hant:
        return "繁體中文"
    }
}

var id: Int {
    self.rawValue
}

}

在我的 DataModel 中，我发布了变量 selectedLanguage

And inside my DataModel, I have published the variable selectedLanguage

final class ModelData: ObservableObject {
    @Published var currentLanguage: Language = Language.zh_hant         
}

我尝试使用选择器让用户更改语言:

I tried to use a picker for the user to change the language:

@EnvironmentObject var modelData: ModelData

在视图主体中:

Picker("Selected Language", selection: modelData.currentLanguage) {
                ForEach(Language.allCases, id: \.rawValue) { language in
                    Text(language.description).tag(language)
                }
            }.pickerStyle(SegmentedPickerStyle()).padding(.horizontal)

它说无法将‘语言’类型的值转换为预期的参数类型‘绑定’"

It says "Cannot convert value of type 'Language' to expected argument type 'Binding'"

如何直接使用picker修改modelData中的currentLanguage?

How can I modify the currentLanguage in the modelData directly with the picker?

推荐答案

你们非常接近.在绑定到 @Published 属性时，您需要使用 $ :

You were very close. You need to use the $ when making a binding to a @Published property like that:

Picker("Selected Language", selection: $modelData.currentLanguage) {
            ForEach(Language.allCases, id: \.id) { language in
                Text(language.description).tag(language)
            }
        }.pickerStyle(SegmentedPickerStyle()).padding(.horizontal)

我还将 id: 更改为 \.id 而不是 \.rawValue 这有点毫无意义，因为它们解析为相同的东西，但在语义上更有意义.

I also changed the id: to \.id rather than \.rawValue which is somewhat meaningless since they resolve to the same thing, but makes a little more sense semantically.

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