@property(nonatomic,readonly)NSInteger numberOfComponents; // 選擇框的行數

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

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

(BOOL)showsSelectionIndicator// 是否顯示選擇指示器 ,即是一個藍色的條

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]; 

#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]; 
} 

// 當用戶選擇某個row時

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

// 當其在繪制row內容,需要row的高度時

(CGFloat) pickerView:(UIPickerView *)pickerView rowHeightForComponent: (NSInteger) component
// 返回指定component.row顯示的文本

(NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger) component
// 當picker view需要給指定的component.row指定view時,調用此函數.返回值為用作row內容的view

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

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

// 返回列數

(NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView
// 返回每一列對應的行數

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

(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]; 

} 

// 獲取指定列的行數

- (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

// 獲取某列選擇的行數

(NSInteger) selectedRowInComponent: (NSInteger) component
// 選擇一行

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

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

- (NSString*)pickerView:(UIPickerView*)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component {
}

- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component {
    [pickerView reloadComponent:1];
}