086设置日期选择器框的显示样式

效果如下：

ViewController.h

#import <UIKit/UIKit.h>

@interface ViewController : UIViewController
@property (strong, nonatomic) UIDatePicker *datePChoice;

@end

ViewController.m

#import "ViewController.h"

@interface ViewController ()
- (void)layoutUI;
- (void)pickerDidChange:(UIDatePicker *)sender;
- (void)buttonDidPush:(UIButton *)sender;
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    
    [self layoutUI];
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

- (void)layoutUI {
    _datePChoice = [[UIDatePicker alloc] initWithFrame:CGRectMake(0, 0, 0, 0)];
    CGPoint newPoint = self.view.center;
    _datePChoice.center = newPoint;
    _datePChoice.datePickerMode = UIDatePickerModeDateAndTime; //默认值是UIDatePickerModeDateAndTime
    [_datePChoice addTarget:self
                     action:@selector(pickerDidChange:) forControlEvents:UIControlEventValueChanged];
    [self.view addSubview:_datePChoice];
    
    UIButton *btnChoice = [[UIButton alloc] initWithFrame:CGRectMake(0, 0, 280, 40)];
    newPoint.y += 160;
    btnChoice.center = newPoint;
    btnChoice.layer.masksToBounds = YES;
    btnChoice.layer.cornerRadius = 10.0;
    btnChoice.layer.borderColor = [UIColor colorWithRed:0.655 green:0.619 blue:0.601 alpha:1.000].CGColor;
    btnChoice.layer.borderWidth = 2.0;
    [btnChoice setTitle:@"切换日期选择器框的显示样式" forState:UIControlStateNormal];
    [btnChoice setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];
    [btnChoice addTarget:self
                  action:@selector(buttonDidPush:)
        forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:btnChoice];
}

- (void)pickerDidChange:(UIDatePicker *)sender {
    NSLog(@"%@", [_datePChoice.date description]); //2015-04-19 11:00:03 +0000；显示时区少了8个钟，所以用NSDateFormatter显示的时间才算正常时区时间
}

- (void)buttonDidPush:(UIButton *)sender {
    //设置日期选择器框的显示样式
    static NSInteger i = 1;
    switch (i%4) {
        case 0:
            _datePChoice.datePickerMode = UIDatePickerModeDateAndTime; //UI效果：4月19日 周日 下午 7 00
            break;
        case 1:
            _datePChoice.datePickerMode = UIDatePickerModeDate; //UI效果：2005年 4月 19日
            break;
        case 2:
            _datePChoice.datePickerMode = UIDatePickerModeTime; //UI效果：下午 7 00
            break;
        case 3:
            _datePChoice.datePickerMode = UIDatePickerModeCountDownTimer; //UI效果：0hours 1min
            break;
    }
    i++;
}

@end