iOS 14 新增 UIDatePicker 的使用及向下兼容
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新的 UIDatePicker 可以作为 inline
的输入控件直接使用,为了向下兼容,可以在 iOS 低版本时提供一个 UITextField
作为默认的输入控件,或 UILabel
仅用来显示。
例如在一个 UITableViewCell
中:
// 在低版本作为输入显示控件,即用户轻触 textField 会显示一个 datePicker 作为输入视图
fileprivate(set) lazy var textField: UITextField = {
let textField = UITextField()
contentView.addSubview(textField)
textField.backgroundColor = .red
textField.translatesAutoresizingMaskIntoConstraints = false
let margins = contentView.layoutMarginsGuide
NSLayoutConstraint.activate([
textField.centerYAnchor.constraint(equalTo: margins.centerYAnchor, constant: yOffset),
textField.trailingAnchor.constraint(equalTo: margins.trailingAnchor),
textField.leadingAnchor.constraint(greaterThanOrEqualTo: detailLabel.trailingAnchor, constant: .tertiaryPadding),
])
return textField
}()
fileprivate(set) lazy var datePicker: UIDatePicker = {
let datePicker = UIDatePicker()
datePicker.datePickerMode = .time
// 兼容性
if #available(iOS 14.0.0, *) {
// iOS 14 之后直接替代 textField 显示
datePicker.preferredDatePickerStyle = .inline
datePicker.translatesAutoresizingMaskIntoConstraints = false
contentView.addSubview(datePicker)
let margins = contentView.layoutMarginsGuide
NSLayoutConstraint.activate([
datePicker.centerYAnchor.constraint(equalTo: margins.centerYAnchor, constant: yOffset),
datePicker.trailingAnchor.constraint(equalTo: margins.trailingAnchor),
datePicker.leadingAnchor.constraint(greaterThanOrEqualTo: detailLabel.trailingAnchor, constant: .tertiaryPadding),
])
} else {
// 较低版本,设置 datePicker 作为 textField 的输入视图
textField.inputView = datePicker
}
return datePicker
}()
使用时,例如在控制器中,可以根据 iOS 版本判断:
guard let reminderTimeCell = cell as? ScheduleConfigureReminderTimeCell else { return }
reminderTimeCell.datePicker.date = schedule.expectedTriggerDate
reminderTimeCell.datePicker.addTarget(self, action: #selector(handleReminderTimeChanged(_:)), for: .valueChanged)
guard #available(iOS 14.0.0, *) else {
// less than iOS 14
reminderTimeCell.textField.text = schedule.expectedTriggerDate.localizedShortTime
return
}