ios7 uidatepicker

@interface  ()

@property (nonatomic, strong) UIDatePicker *myDatePicker;
@end

- (void)viewDidLoad{
    [super viewDidLoad];
    
    self.myDatePicker = [[UIDatePicker alloc] init];
    //居中
    self.myDatePicker.center = self.view.center;
    //UIDatePickerModeCountDownTimer :日期选择器显示小时和分钟的值
    self.myDatePicker.datePickerMode = UIDatePickerModeCountDownTimer;
    //添加到view
    [self.view addSubview:self.myDatePicker];
    //启动默认时间间隔 0hours 2min
    NSTimeInterval twoMinutes = 2 * 60;
    //设置默认倒数时间
    [self.myDatePicker setCountDownDuration:twoMinutes];
}