代码 实现UIDatePicker控件 和 Tab Bar 视图切换

  感觉代码写控件都一个理，先在ViewDidLoad中创建控件对象，然后初始化他的frame，在简单的描叙下他们的相关属性，最后在添加到视图上；这样控件就在视图上显示出来了；

        UIDatePicker是一个用来选择日期或设置日期的控件，他不是UIPickerView子类，而是UIControl的子类，当然它所依赖的类也是与实践有关的类，NSDate；苹果公司已经为你实现好了这个控件是怎么实现的，它底层怎么实现你不必了解，你只需调用相关API就可以了；

        上一文中写了Navigation Bar   和ToolBar的视图切换，这一节把Tab Bar视图切换也加上，切换两个不同格式下的日历表，还是先把效果图奉上吧(界面不咋好看):

前面两个tab Bar item图标是系统的图标，后面一个是添加了一张背景图片，但是不知道问什么没有显示，切换界面的两个按钮还是前面两个Tab Bar Item； 

1.创建一个新工程叫DatePickerDemo； File->New->Project ->single View Application -> next

然后在新建两个ViewController分别叫FirstViewController和SecondViewController

2.设置UITabBarDelegate协议，在ViewController中，

#import <UIKit/UIKit.h> #import "FirstViewController.h" #import "SecondViewController.h" @interface ViewController : UIViewController<UITabBarDelegate> {     UIDatePicker *datePicker;     UITabBar *tabBar;     FirstViewController *firstViewController;     SecondViewController *secondViewCOntroller; }  @end

- (void)viewDidLoad {     [super viewDidLoad]; 	// Do any additional setup after loading the view, typically from a nib. //    初始化Tab Bar     tabBar = [[UITabBar alloc] initWithFrame:CGRectMake(0, 416, 320, 44)];   //设置Tab Bar上的交互属性为YES     [tabBar setUserInteractionEnabled:YES]; //    设置代理     [tabBar setDelegate:self]; //    设置TabBar的背景颜色     [tabBar setBackgroundColor:[UIColor purpleColor]]; //    设置tabBar的透明度     tabBar.alpha = 0.5f;      //    定义一个可变数组存放tab Bar Item     NSMutableArray *tabBarArray= [NSMutableArray array]; //    初始化一个Tab Bar Item  到数组中     [tabBarArray addObject:[[UITabBarItem alloc]initWithTabBarSystemItem:UITabBarSystemItemFavorites                                                                      tag:1]];     [tabBarArray addObject:[[UITabBarItem alloc]initWithTabBarSystemItem:UITabBarSystemItemHistory                                                                      tag:2]];          UIImage *image = [UIImage imageNamed:@"test48.png"];     [tabBarArray addObject:[[UITabBarItem alloc]initWithTitle:@"测试" image:image tag:3]];      //    给Tab Bar 添加数组里的tab Bar Item     [tabBar setItems:tabBarArray animated:NO];     [self.view addSubview:tabBar];       //    datePicker宽度320像素和高度216像素，系统都设置好了，只需设置一下他的远点坐标，     datePicker = [[UIDatePicker alloc] initWithFrame:CGRectMake(0, 0, 0, 0)];      //    设置datePicker显示模式     [datePicker setDatePickerMode:UIDatePickerModeDateAndTime];      //DatePicker属于UIControl子类，可以触发事件，当滚动滑轮滑轮停下后就调用这个方法了     [datePicker addTarget:self action:@selector(dateChanged:) forControlEvents:UIControlEventValueChanged];          [self.view addSubview:datePicker];     } 

[datePickersetDatePickerMode:UIDatePickerModeDateAndTime];设置日历显示模式，有四种模式

typedefenum {  

 UIDatePickerModeDateAndTime,

    UIDatePickerModeTime,            

    UIDatePickerModeDate,            

    UIDatePickerModeCountDownTimer    

} UIDatePickerMode;

4. 设置日历控件的响应事件

-(void)dateChanged:(id)sender {     UIDatePicker *control = (UIDatePicker*)sender; //    把当前控件设置的时间赋给date     NSDate *date = control.date; //    将NSDate格式装换成NSString类型     NSDateFormatter *dateFormatter = [[NSDateFormatter alloc]init]; //    设置日历显示格式     [dateFormatter setDateFormat:@"yyyy-MM-dd HH:mm:ss"]; //    把日历时间传给字符串     NSString *strDate = [dateFormatter stringFromDate:date];          NSString *message = [[NSString alloc]initWithFormat:@"你选取的时间是：%@",strDate]; //      弹出一个警告                       UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"温馨提示"                                                     message:message                                                    delegate:self                                           cancelButtonTitle:@"OK"                                           otherButtonTitles: nil]; //    显示警告     [alert show];  } 

NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init]; [dateFormatter setDateFormat:@"yyyy-MM-dd HH:mm:ss"]; NSString *strDate = [dateFormatter stringFromDate:[NSDate date]]; NSLog(@"%@", strDate);

NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init]; [dateFormatter setDateFormat:@"yyyy-MM-dd HH:mm:ss"]; NSDate *date = [dateFormatter dateFromString:@"2012-07-04 9:03:03"]; NSLog(@"%@", date)

5.UITabBarDelegate的委托方法

-(void)tabBar:(UITabBar *)tabBarBar didSelectItem:(UITabBarItem *)item {          if (item.tag == 1) {      //   [tabBar setSelectedItem:[tabBar.items objectAtIndex:0]];         NSLog(@"---->%d",item.tag);         if(firstViewController.view.superview==nil)         {             if (firstViewController.view==nil) {                            FirstViewController *firstView = [[FirstViewController alloc]initWithNibName:@"FirstViewController" bundle:nil];             firstViewController=firstView;             }             [secondViewCOntroller.view removeFromSuperview]; //            [self.view insertSubview:firstViewController.view atIndex:0];             [self.view  addSubview:firstViewController.view];         }         else {             [secondViewCOntroller.view removeFromSuperview]; //              [self.view insertSubview:firstViewController.view atIndex:0];             [self.view  addSubview:firstViewController.view];          }                   }     if (item.tag == 2) {                 if (secondViewCOntroller.view.superview==nil) {             if (secondViewCOntroller.view == nil)             {                              SecondViewController *secondView = [[SecondViewController alloc] initWithNibName:@"SecondViewController" bundle:nil];             secondViewCOntroller=secondView;             }             [firstViewController.view removeFromSuperview];             [self.view insertSubview:secondViewCOntroller.view atIndex:0];          }         else {             [firstViewController.view removeFromSuperview];             [self.view insertSubview:secondViewCOntroller.view atIndex:0];          }                  }                    NSLog(@"---->%d",item.tag); }

            [self.view insertSubview:firstViewController.view atIndex:0];

            [self.view addSubview:firstViewController.view];

在方法中我把第一个给注释了，第一个是插入主视图后面，出现的情况就是主视图上的DatePicker把插入给覆盖了，显示不出来，第二种是之间把切换的视图放在主视图上面，但是这个问题出来了，他把主视图下面的Tab Bar给覆盖了，于是我把需要切换的视图的frame高度设置成了460-44高度，在FirstViewController的ViewDidLoad方法中

- (void)viewDidLoad { [super viewDidL

oad]; // Do any additional setup after loading the view from its nib. self.view.frame = CGRectMake(0, 0, 320, 416); self.view.backgroundColor = [UIColor blueColor]; UIDatePicker *datePicker = [[UIDatePicker alloc] initWithFrame:CGRectMake(0, 0, 0, 0)]; // 设置datePicker显示模式 [datePicker setDatePickerMode:UIDatePickerModeTime]; [self.view addSubview:datePicker]; }

- (void)viewDidLoad {     [super viewDidLoad];     // Do any additional setup after loading the view from its nib.     self.view.backgroundColor = [UIColor greenColor];     UIDatePicker *datePicker = [[UIDatePicker alloc] initWithFrame:CGRectMake(0, 0, 0, 0)];          //    设置datePicker显示模式     [datePicker setDatePickerMode:UIDatePickerModeDate];     [self.view addSubview:datePicker]; }

附上源代码:http://download.csdn.net/detail/duxinfeng2010/4409646

     本文转自新风作浪 51CTO博客，原文链接：http://blog.51cto.com/duxinfeng/1208748，如需转载请自行联系原作者