SwiftUI 禁用拖动功能

Question

我有一个简单的视图，其中包含一组按钮，允许根据条件拖动功能。如何根据条件禁用 .onDrag？.disabled 仅禁用点击功能。

    ScrollView
    {
        ForEach(animals, id: \.id)
        {
            animal in
            Button(action:{})
            {
               Text(animal.name)
            }
                .disabled(!animal.isEnable)
                .onDrag
                {
                    let provider = NSItemProvider(object: animal.name as NSString )
                    provider.suggestedName = animal.name
                    return provider
                }
          }
    }

Answer 1

这是一个带有辅助修饰符的解决方案。使用 Xcode 11.4 进行测试。

// @available(iOS 13.4, *) - needed for iOS
struct Draggable: ViewModifier {
    let condition: Bool
    let data: () -> NSItemProvider

    @ViewBuilder
    func body(content: Content) -> some View {
        if condition {
            content.onDrag(data)
        } else {
            content
        }
    }
}

// @available(iOS 13.4, *) - needed for iOS
extension View {
    public func drag(if condition: Bool, data: @escaping () -> NSItemProvider) -> some View {
        self.modifier(Draggable(condition: condition, data: data))
    }
}

并更新你的代码是

ForEach(animals, id: \.id)
{
    animal in
    Button(action:{})
    {
        Text(animal.name)
    }
    .disabled(!animal.isEnable)
    .drag(if: animal.isEnable) {     // << here !!
        let provider = NSItemProvider(object: animal.name as NSString )
        provider.suggestedName = animal.name
        return provider
    }
}