SwiftUI中由@Binding String创建的Binding<Double>无法更新UI问题求助

架构老林

2026-8-15

问题：自定义Binding<Double?>绑定UIKit TextField后收起键盘值消失

现有代码

视图初始化器与属性

我通过以下初始化器传入Binding<String>：

let placeholderString: String
let imageName: String
let keyboardType: UIKeyboardType
let fieldType: DataFieldType
@Binding var fieldName: String // 此处的变量
private var isFocused: FocusState<Bool>.Binding
@State private var frame = CGRect.zero

init(placeholderString: String, imageName: String, keyboardType: UIKeyboardType, fieldType: DataFieldType, fieldName: Binding<String>, focusState: FocusState<Bool>.Binding) {
    self.placeholderString = placeholderString
    self.imageName = imageName
    self.keyboardType = keyboardType
    self.fieldType = fieldType
    self._fieldName = fieldName // 此处的变量
    self.isFocused = focusState
}

将这个String类型的Binding用于SwiftUI原生TextField时功能正常。

自定义Double?绑定

我创建了一个生成Binding<Double?>的自定义绑定，代码如下：

private var doubleBinding: Binding<Double?> {
    get {
        guard let binding = Double(fieldName) else { return .constant(nil) }
        return .constant(binding)
    }
    set {
        guard let double = newValue.wrappedValue else { return }
        fieldName = String(double)
    }
}

我将此绑定用于一个基于UIKit构建的、初始化器接收Binding<Double>的自定义TextField。