代碼實現UIPickerView

         先說一下當個組件選取器，我們創建一個數組NSAray來保存選取器中的內容；選取器本身不會儲存任何數據，，它通過調用數據源和委托方法來顯示數據；但是對于大量數據的數據源，數組并不合適，我們可以做一個靜態列表如plist文件或者URL載入，和后面將講在文件中獲取數據，還以多個選取器的之間的關聯如何實現；先說下簡單的單個選取器:

先把效果圖貼出來

1.新建工程名為PickerViewDemo ， File->New->Project ->single View Application -> next

2.在視圖上添加選取器

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

選取器上顯示數據，必須依賴兩個協議，UIPickerViewDelegate和UIPickerViewDataSource，把他們添加到ViewController.h文件中

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

- (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; //    顯示選中框     pickerView.showsSelectionIndicator=YES;     [self.view addSubview:pickerView];           NSArray *dataArray = [[NSArray alloc]initWithObjects:@"許嵩",@"周杰倫",@"梁靜茹",@"許飛",@"鳳凰傳奇",@"阿杜",@"方大同",@"林俊杰",@"胡夏",@"邱永傳", nil];          pickerData=dataArray;      //     添加按鈕        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];      }

#pragma mark - #pragma mark Picker Date Source Methods  //返回顯示的列數 -(NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView {     return 1; } //返回當前列顯示的行數 -(NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component {     return [pickerData count]; }  #pragma mark Picker Delegate Methods  //返回當前行的內容,此處是將數組中數值添加到滾動的那個顯示欄上 -(NSString*)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component {     return [pickerData objectAtIndex:row]; }

說一下兩個協議實例方法,參考http://www.cnblogs.com/edsioon/

UIPickerViewDelegate中的實例方法

5.關于按鈕響應事件，關于按鈕的形成和添加響應事件不再提，前面都有，

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

[pickerViewselectedRowInComponent:0];方法返回當前被選中的索引序號，這是UIPickerView的實例方法，在官方文檔中

UIPickerView還有其他實例方法

- (NSInteger) numberOfRowsInComponent:(NSInteger)component

參數為component的序號(從左到右,以0起始),返回指定的component中row的個數

-(void) reloadAllComponents

調用此方法使得PickerView向delegate: Query for new data for all components

-(void) reloadComponent: (NSInteger) component

參數為需更新的component的序號,調用此方法使得PickerView向其delegate: Query for new data

-(CGSize) rowSizeForComponent: (NSInteger) component

參數為component的序號,返回值為the size of rows in the given components, picker view 通過調用委托方法中的pickerView:widthForComponent:和pickerView:rowHeightForComponent:獲得返回值

-(NSInteger) selectedRowInComponent: (NSInteger) component

參數為component的序號,返回被選中row的序號,若無row被選中,則返回-1

-(void) selectRow: (NSInteger)row inComponent: (NSInteger)component animated: (BOOL)animated

作用:在代碼指定要選擇的某component的某row

參數:row序號,component序號,BOOL值(若為YES,轉動spin到你選擇的新值,若為NO,直接顯示你選擇的值)

-(UIView *) viewForRow: (NSInteger)row forComponent: (NSInteger)component

參數:row序號,component序號,返回由委托方法pickerView:viewForRow:forComponentreusingView:指定的view.如果委托對象并沒有實現這個方法,或者說這個view并不是可見的,則返回nil

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