如何在 SwiftUI 的 DatePicker 中设置 countDownTimer 模式? [英] How can I set countDownTimer mode in DatePicker on SwiftUI?

问题描述

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?

With UIKit, the UIDatePicker allow set mode to UIDatePicker.Mode.countDownTimer and we can have set duration.

With SwiftUI, I don't see any native way to solve this. The only way would be doing interface with UIKit?

[更新]
仅找到解决方案

[UPDATE]
Only solution found

DurationPickerView.swift

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
}

推荐答案

现在获得倒计时行为的唯一方法是将 UIDatePicker 包装在自定义视图中.

The only way to get the countdown behavior right now is by wrapping UIDatePicker in a custom view.

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

Here is a simplified version of Ailton Vieira Pinto Filho's code using 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
        }
    }
}

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