如何在 SwiftUI 的 DatePicker 中设置 countDownTimer 模式？

Question

使用 UIKit，UIDatePicker 允许设置模式为 UIDatePicker.Mode.countDownTimer，我们可以设置持续时间。

使用 SwiftUI，我看不到任何解决此问题的本机方法。唯一的方法是与 UIKit 交互？

[更新]
仅找到解决方案

DurationPickerView.swift

import SwiftUI
import UIKit

struct DurationPickerView: UIViewRepresentable {
    @Binding var time: Time

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

    func makeUIView(context: Context) -> UIDatePicker {
        let datePicker = UIDatePicker()
        datePicker.datePickerMode = .countDownTimer
        datePicker.addTarget(context.coordinator, action: #selector(Coordinator.onDateChanged), for: .valueChanged)
        return datePicker
    }

    func updateUIView(_ datePicker: UIDatePicker, context: Context) {
        let date = Calendar.current.date(bySettingHour: time.hour, minute: time.minute, second: time.second, of: datePicker.date)!
        datePicker.setDate(date, animated: true)
    }

    class Coordinator: NSObject {
        var durationPicker: DurationPickerView

        init(_ durationPicker: DurationPickerView) {
            self.durationPicker = durationPicker
        }

        @objc func onDateChanged(sender: UIDatePicker) {
            print(sender.date)
            let calendar = Calendar.current
            let date = sender.date
            durationPicker.time = Time(hour: calendar.component(.hour, from: date), minute: calendar.component(.minute, from: date), second: calendar.component(.second, from: date))
        }
    }
}

时间.swift

import Foundation

struct Time {
    var hour: Int
    var minute: Int
    var second: Int = 0
}

Answer 1

现在获得倒计时行为的唯一方法是包装UIDatePicker在自定义视图中。

这是Ailton Vieira Pinto Filho 的代码的简化版本，使用countDownDuration.

import SwiftUI

struct DurationPicker: UIViewRepresentable {
    @Binding var duration: TimeInterval

    func makeUIView(context: Context) -> UIDatePicker {
        let datePicker = UIDatePicker()
        datePicker.datePickerMode = .countDownTimer
        datePicker.addTarget(context.coordinator, action: #selector(Coordinator.updateDuration), for: .valueChanged)
        return datePicker
    }

    func updateUIView(_ datePicker: UIDatePicker, context: Context) {
        datePicker.countDownDuration = duration
    }

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

    class Coordinator: NSObject {
        let parent: DurationPicker

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

        @objc func updateDuration(datePicker: UIDatePicker) {
            parent.duration = datePicker.countDownDuration
        }
    }
}