运行 在 SwiftUI didSet 函数中更改 DatePicker 中的日期时的代码？

Question

struct ViewName: View {
    @State private var selectedDay: Date = Date() {
        didSet {
            print("Old value was \(oldValue) and new date is \(self.selectedDay)")
        }
    }
    var body: some View {
        VStack {
            DatePicker(selection: $selectedDay, in: Date()..., displayedComponents: .date) { Text("") }
        }
    }
}

我的问题是，当我在 DatePicker 中设置 selectedDate 值时，为什么没有任何内容打印到控制台？

Answer 1

My question is, when I'm setting the selectedDate value in the DatePicker, why is there nothing printed to the console?

目前 didSet 不适用于 @State 属性 包装器。

这是一种对 DatePicker 选择产生副作用的方法已更改

struct ViewName: View {
    @State private var selectedDay = Date()

    var body: some View {
        let dateBinding = Binding(
            get: { self.selectedDay },
            set: {
                print("Old value was \(self.selectedDay) and new date is \([=10=])")
                self.selectedDay = [=10=]
            }
        )
        return VStack {
            DatePicker(selection: dateBinding, in: Date()..., displayedComponents: .date) { Text("") }
        }
    }
}