textFieldDidChangeSelection:在视图更新期间修改状态,这将导致未定义的行为

时间:2019-11-15 14:24:06

标签: ios swift uikit swiftui

这是我的代码:

struct CustomTextField: UIViewRepresentable {
    var placeholder: String
    @Binding var text: String

    func makeUIView(context: UIViewRepresentableContext<CustomTextField>) -> UITextField {
        let uiView = UITextField()
        uiView.delegate = context.coordinator

        return uiView
    }

    func updateUIView(_ uiView: UITextField, context: UIViewRepresentableContext<CustomTextField>) {
        uiView.placeholder = placeholder
        uiView.text = text

        if uiView.window != nil, !uiView.isFirstResponder {
            uiView.becomeFirstResponder()
        }
    }

    func makeCoordinator() -> Coordinator {
        Coordinator(self)
    }

    class Coordinator: NSObject, UITextFieldDelegate {
        var parent: CustomTextField

        init(_ CustomTextField: CustomTextField) {
            self.parent = CustomTextField
        }

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

构建不会引起警告,但是在模拟器中使用CustomTextField会引起警告。

这是警告:

  

在视图更新期间修改状态,这将导致未定义的行为。

它显示在这一行:

parent.text = textField.text ?? ""

如何摆脱此警告?我在做什么错了?

1 个答案:

答案 0 :(得分:0)

尝试异步执行修改:

func textFieldDidChangeSelection(_ textField: UITextField) {
    DispatchQueue.main.async {
        parent.text = textField.text ?? ""
    }
}