如何从 UIDatePicker countDownTimer 模式获取数据

Question

我在 AlertController 上有处于 countDownTimer 模式的 UIDatePicker。 我想保存值，用户在按下设置按钮时会选择变量。 我该怎么做？ 我现在的代码：

func showAlert() {
    let vc = UIViewController()
    vc.preferredContentSize = CGSize(width: 250,height: 300)
    let pickerView = UIDatePicker(frame: CGRect(x: 0, y: 0, width: 250, height: 300))
    pickerView.datePickerMode = .countDownTimer
    vc.view.addSubview(pickerView)
    let alert = UIAlertController(title: "Sleep Timer", message: "Please, choose hours and minutes", preferredStyle: UIAlertController.Style.alert)
    alert.setValue(vc, forKey: "contentViewController")
    alert.addAction(UIAlertAction(title: "Set", style: .default, handler: nil))
    alert.addAction(UIAlertAction(title: "Cancel", style: .cancel, handler: nil))
    self.present(alert, animated: true)
}

Answer 1

通常，您可以访问选择器的countDownDuration属性来获取秒值。

它的范围在 0 到 86,340 秒之间。

let seconds = pickerView.countDownDuration

---

对于您所需的情况，您有很多选择。 其中2个是：

更轻松

    func showAlert() {
        let vc = UIViewController()
        vc.preferredContentSize = CGSize(width: 250,height: 300)
        let pickerView = UIDatePicker(frame: CGRect(x: 0, y: 0, width: 250, height: 300))
        pickerView.datePickerMode = .countDownTimer
        //Your required line
        pickerView.addTarget(self, action: #selector(onDurationChanged), for: .valueChanged)
        vc.view.addSubview(pickerView)
        let alert = UIAlertController(title: "Sleep Timer", message: "Please, choose hours and minutes", preferredStyle: UIAlertController.Style.alert)
        alert.setValue(vc, forKey: "contentViewController")
        alert.addAction(UIAlertAction(title: "Set", style: .default, handler: nil))
        alert.addAction(UIAlertAction(title: "Cancel", style: .cancel, handler: nil))
        self.present(alert, animated: true)
    }
    
    @objc private func onDurationChanged(_ picker: UIDatePicker) {
        let seconds = picker.countDownDuration
        //Do something with duration
    }

更清洁的方式

您可以为选择器选择创建一个小型 VC，然后您可以更好地分离关注点：

class PickerViewController: UIViewController {
    var duration: TimeInterval = 0
    
    let pickerView: UIDatePicker = {
        let picker = UIDatePicker(frame: CGRect(x: 0, y: 0, width: 250, height: 300))
        picker.datePickerMode = .countDownTimer
        picker.addTarget(self, action: #selector(onDurationChanged), for: .valueChanged)
        return picker
    }()
    
    @objc private func onDurationChanged(_ picker: UIDatePicker) {
        duration = picker.countDownDuration
    }
}

class ViewController: UIViewController {
    func showAlert() {
        let vc = PickerViewController()
        vc.preferredContentSize = CGSize(width: 250,height: 300)
        let alert = UIAlertController(title: "Sleep Timer", message: "Please, choose hours and minutes", preferredStyle: UIAlertController.Style.alert)
        alert.setValue(vc, forKey: "contentViewController")
        alert.addAction(UIAlertAction(title: "Set", style: .default, handler: { action in
            let seconds = vc.duration
            //Do something.
        }))
        alert.addAction(UIAlertAction(title: "Cancel", style: .cancel, handler: nil))
        self.present(alert, animated: true)
    }
}