//星期 月日 时分 上下午
UIDatePicker *dk = [[UIDatePicker alloc] initWithFrame:CGRectMake(0, 20, 320, 200)];
    [self.view addSubview:dk];
    //四种 类型 
    dk.datePickerMode = UIDatePickerModeCountDownTimer;
/*
    UIDatePickerModeTime,           // Displays hour, minute, and optionally AM/PM designation depending on the locale setting (e.g. 6 | 53 | PM)
    UIDatePickerModeDate,           // Displays month, day, and year depending on the locale setting (e.g. November | 15 | 2007)
    UIDatePickerModeDateAndTime,    // Displays date, hour, minute, and optionally AM/PM designation depending on the locale setting (e.g. Wed Nov 15 | 6 | 53 | PM)
    UIDatePickerModeCountDownTimer, // Displays hour and minute (e.g. 1 | 53)
 */   
 dk.minuteInterval = 5;//被60整除的数 显示时间间隔
  
 dk.minimumDate = //NSDate  最小时间
 //NSDate* minDate = [[NSDate alloc]initWithString:@"1900-01-01 00:00:00 -0500"];
    dk.maximumDate =   //NSDate  最大时间
     
    dk.date =  //设置默认显示日期
    //添加事件
    [dk addTarget:self action:@selector(clickDatePicker:) forControlEvents:UIControlEventValueChanged];