无法分配给属性:“$text"是不可变的 [英] Cannot assign to property: '$text' is immutable

问题描述

我想在 SwiftUI 中创建一个自定义文本字段来处理第一响应者，但是我在代码中出现了这个错误并且结构是不可变的我不知道我该怎么办?

I wanted to make a custom textfield in SwiftUI to can handle first responder but I had this error in the code and struct is immutable I don't know what should I do?

struct CustomTextField: UIViewRepresentable {
class Coordinator: NSObject, UITextFieldDelegate {

    @Binding var text: String
    var didBecomeFirstResponder = false

    init(txt: Binding<String>) {
        self.$text = txt
    }

    func textFieldDidChangeSelection(_ textField: UITextField) {
        text = textField.text ?? ""
    }

}

@Binding var text: String
var isFirstResponder: Bool = false

func makeUIView(context: UIViewRepresentableContext<CustomTextField>) -> UITextField {
    let textField = UITextField(frame: .zero)
    textField.delegate = context.coordinator
    return textField
}

func makeCoordinator() -> CustomTextField.Coordinator {
    return Coordinator(txt: $text)
}

func updateUIView(_ uiView: UITextField, context: UIViewRepresentableContext<CustomTextField>) {
    uiView.text = text
    if isFirstResponder && !context.coordinator.didBecomeFirstResponder  {
        uiView.becomeFirstResponder()
        context.coordinator.didBecomeFirstResponder = true
    }
}
}

推荐答案

在 beta 4 中，属性包装器的实现发生了变化.

In beta 4, the implementation of property wrappers changed.

在 beta 3 之前，这是有效的:

Until beta 3, this was valid:

   self.$text = txt

在测试版 4 中，它更改为:

In beta 4, it changed to:

   self._text = txt

检查实现上的差异，在我发布的另一个问题中:

Check for the difference in implementation, in this other question I posted:

https://stackoverflow.com/a/57088052/7786555

了解更多详情:

https://stackoverflow.com/a/56975728/7786555

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