Swift - UIDatePicker

import UIKit

class ViewController: UIViewController{
    override func viewDidLoad() {
        super.viewDidLoad()
        //创建DatePicker
        let datePicker = UIDatePicker()
        //设置位置
        datePicker.center = self.view.center
        //设置tag(可通过tag来获取其对象)
        datePicker.tag = 1
        //设置显示模式为日期时间
        datePicker.datePickerMode = UIDatePicker.Mode.dateAndTime
        //设置最大值，最小值
        datePicker.maximumDate = Date(timeInterval:3*24*60*60,since:Date())//设置最大值为现在时间往后三天以内
        datePicker.minimumDate = Date()//设置最小值为现在
        //添加到视图中
        self.view.addSubview(datePicker)
        //添加确定按钮
        let button = UIButton(frame: CGRect(x: 50, y: 400, width: 250, height: 50))
        button.backgroundColor = UIColor.yellow
        button.setTitle("确定", for: .normal)
        button.addTarget(self, action: #selector(ViewController.getValue), for: .touchUpInside)
        self.view.addSubview(button)
    }
    @objc func getValue()
    {
        let datePicker = self.view.viewWithTag(1)as! UIDatePicker//通过tag获取datePicker对象
        let date = datePicker.date//获取选定的值
        //初始化日期格式化对象
        let dateFormatter = DateFormatter()
        //设置日期格式化对象的具体格式
        dateFormatter.dateFormat = "yyyy-MM-dd HH:mm"
        //将选定的值转换为string格式以设定格式输出
        let dateAndTime = dateFormatter.string(from: date)
        print(dateAndTime)
    }
}