Question

我有一个包含三个文本字段的SwiftUI屏幕。当您运行代码并点击清除按钮时，您将看到三个完全空白的文本字段。可以预期的是，您会看到占位符文本，但是仅在每个文本字段获得焦点（即用户在字段内轻按）时才会显示。

class UserInput: ObservableObject {
    @Published var text1 = "some text"
    @Published var text2 = "some more text"
    @Published var text3 = "and this is the final input"

    func clear() {
        self.text1 = ""
        self.text2 = ""
        self.text3 = ""
    }
}

struct ContentView: View {
    @ObservedObject var userInput = UserInput()

    var body: some View {
        Form {
            TextField("Type something in text1", text: self.$userInput.text1)
            TextField("Type something in text2", text: self.$userInput.text2)
            TextField("Type something in text3", text: self.$userInput.text3)
            Button("Clear all fields", action: self.userInput.clear)
        }
    }
}

我是否缺少某些东西，或者是否有针对此行为的解决方法？

Answer 1

我找到了解决方法。基本上，我发送一个用户永远无法键入的特殊字符，然后捕获该字符并在表单本身中“本地”清除字段。它可以正常工作，并按预期恢复占位符。

随着变通办法的进行，这一步很难看。

class UserInput: ObservableObject {
    static let clearCode = String.Element(Unicode.Scalar(7))
    @Published var text1 = "some text"
    @Published var text2 = "some more text"
    @Published var text3 = "and this is the final input"

    func clear() {
        self.text1 = String(Self.clearCode)
        self.text2 = String(Self.clearCode)
        self.text3 = String(Self.clearCode)
    }
}

struct ContentView: View {
    @ObservedObject var userInput = UserInput()

    var body: some View {
        Form {
            TextField("Type something in text1", text: self.$userInput.text1)
                .onReceive(self.userInput.text1.publisher) { newValue in
                    if newValue == UserInput.clearCode {
                        self.userInput.text1 = ""
                    }
                }
            TextField("Type something in text2", text: self.$userInput.text2)
                .onReceive(self.userInput.text2.publisher) { newValue in
                    if newValue == UserInput.clearCode {
                        self.userInput.text2 = ""
                    }
                }
            TextField("Type something in text3", text: self.$userInput.text3)
                .onReceive(self.userInput.text3.publisher) { newValue in
                    if newValue == UserInput.clearCode {
                        self.userInput.text3 = ""
                    }
                }
            Button("Clear all fields", action: self.userInput.clear)
        }
    }
}

我尝试了以下解决方案，但未提供解决方法，但仍清除了占位符。

class UserInput: ObservableObject {
    let clearPublisher = PassthroughSubject<Bool, Never>()

    // ...
    func clear() {
        self.clearPublisher.send(true)
    }
}

struct ContentView: View {
            // ...
            TextField("Type something in text1", text: self.$userInput.text1)
                .onReceive(self.userInput.clearPublisher) { _ in
                    self.userInput.text1 = "" 
                }
            // ...

清除SwiftUI TextField不会还原占位符

1 个答案: