UIPickerView(滚动选择控制器)

1.UIPickerView的宽度和高度是固定的,纵向是320216,横向是568162

2.属性:

@property(nonatomic,readonly)NSInteger numberOfComponents; // 选择框的行数

@property(nonatomic,assign)idUIPickerViewDataSource> dataSource; (类似于UITableView)

@property(nonatomic,assign)idUIPickerViewDelegate>delegate; (类似于UITableView)

(BOOL)showsSelectionIndicator// 是否显示选择指示器 ,即是一个蓝色的条

pickerView = [[UIPickerView alloc] initWithFrame:CGRectMake(0, 0, 320, 216)];  
//    指定Delegate  
    pickerView.delegate=self;  
//    显示选中框  
    pickerView.showsSelectionIndicator=YES;  
    [self.view addSubview:pickerView];

以上可以在视图显示一个选取器，但是内容空白，pickerView.showsSelectionIndicator=YES;是这只当前选取器所选中的内容：

选取器上显示数据，必须依赖两个协议，UIPickerViewDelegate和UIPickerViewDataSource，把他们添加到ViewController.h文件中

#import <UIKit/UIKit.h>  
  
@interface ViewController : UIViewController<UIPickerViewDelegate,UIPickerViewDataSource>  
{  
  
    UIPickerView *pickerView;  
    NSArray *pickerData;  
  
}  
  
@end

3.然后在.m文件的ViewDidLoad中初始化界面

- (void)viewDidLoad  
{  
    [super viewDidLoad];  
    // Do any additional setup after loading the view, typically from a nib.  
      
    pickerView = [[UIPickerView alloc] initWithFrame:CGRectMake(0, 0, 320, 216)];  
//    指定Delegate  
    pickerView.delegate=self;  
//    显示选中框  
    pickerView.showsSelectionIndicator=YES;  
    [self.view addSubview:pickerView];   
      
    NSArray *dataArray = [[NSArray alloc]initWithObjects:@"许嵩",@"周杰伦",@"梁静茹",@"许飞",@"凤凰传奇",@"阿杜",@"方大同",@"林俊杰",@"胡夏",@"邱永传", nil];  
      
    pickerData=dataArray;  
      
//     添加按钮     
    CGRect frame = CGRectMake(120, 250, 80, 40);  
    UIButton *selectButton = [UIButton buttonWithType:UIButtonTypeRoundedRect];  
    selectButton.frame=frame;  
    [selectButton setTitle:@"SELECT" forState:UIControlStateNormal];  
      
    [selectButton addTarget:self action:@selector(buttonPressed:) forControlEvents:UIControlEventTouchUpInside];  
      
    [self.view addSubview:selectButton];  
      
}

4.实现UIPickerView的代理方法，将数据显示在选取器上所需要几个方法

#pragma mark -  
#pragma mark Picker Date Source Methods  
  
//返回显示的列数  
-(NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView  
{  
    return 1;  
}  
//返回当前列显示的行数  
-(NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component  
{  
    return [pickerData count];  
}  
  
#pragma mark Picker Delegate Methods  
  
//返回当前行的内容,此处是将数组中数值添加到滚动的那个显示栏上  
-(NSString*)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component  
{  
    return [pickerData objectAtIndex:row];  
}

前两个是数据源的代理方法，一个是返回列，有几个选取器就返回几，第二个是设置选取器有多少行，因为就这一个选取器，所以直接返回行数，即数组元素个数多少；第三个代理方法是将数组元素添加到了选取器上面显示；

说一下两个协议实例方法,参考http://www.cnblogs.com/edsioon/

UIPickerViewDelegate中的实例方法

// 当用户选择某个row时

- (void) pickerView: (UIPickerView *)pickerView didSelectRow: (NSInteger)row inComponent: (NSInteger)component

// 当其在绘制row内容,需要row的高度时

(CGFloat) pickerView:(UIPickerView *)pickerView rowHeightForComponent: (NSInteger) component

// 返回指定component.row显示的文本

(NSString )pickerView:(UIPickerView )pickerView titleForRow:(NSInteger)row forComponent:(NSInteger) component

// 当picker view需要给指定的component.row指定view时,调用此函数.返回值为用作row内容的view

(UIView )pickerView: (UIPickerView )pickerView view ForRow:(NSInteger) row forComponent:(NSInteger) component reusingView:(UIView *) view

// row的宽度

(CGFloat)pickerView: (UIPickerView *)pickerView widthForComponent:(NSInteger) component

UIPickerViewDataSource 中的实例方法

按照官方文档的说法,UIPickerViewDataSource这个协议仅有的功能就是提供picker view中component的个数和各个component中的row的个数,虽然名为datasource,但是它工作于MVC的C中

本协议仅有两个实例方法,均需要实现:

// 返回列数

(NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView

// 返回每一列对应的行数

(NSInteger) pickerView:(UIPickerView *) pickerView numberOfRowsInComponent:(NSInteger) component

5.关于按钮响应事件，关于按钮的形成和添加响应事件不再提，前面都有，

(void) buttonPressed:(id)sender  
{  
     NSInteger row =[pickerView selectedRowInComponent:0];  
     NSString *selected = [pickerData objectAtIndex:row];  
     NSString *message = [[NSString alloc] initWithFormat:@"你选择的是:%@",selected];  
      
    UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"提示"   
                                                    message:message  
                                                   delegate:self  
                                          cancelButtonTitle:@"OK"  
                                          otherButtonTitles: nil];  
    [alert show];  
      
}

@UIPickerView还有其他实例方法

// 获取指定列的行数

- (NSInteger) numberOfRowsInComponent:(NSInteger)component

// 刷新所有的列

(void) reloadAllComponents

// 刷新指定的列

(void) reloadComponent: (NSInteger) component
(CGSize) rowSizeForComponent: (NSInteger) component

// 获取某列选择的行数

(NSInteger) selectedRowInComponent: (NSInteger) component

// 选择一行

(void) selectRow: (NSInteger)row inComponent: (NSInteger)component animated: (BOOL)animated
(UIView *) viewForRow: (NSInteger)row forComponent: (NSInteger)component

附上源代码: http://download.csdn.net/detail/duxinfeng2010/4410909