1.UIPickerView的寬度和高度是固定的,縱向是320*216,橫向是568*162
2.屬性:
@property(nonatomic,readonly)NSIntegernumberOfComponents; // 選擇框的行數
@property(nonatomic,assign)id<UIPickerViewDataSource> dataSource; (類似于UITableView)
@property(nonatomic,assign)id<UIPickerViewDelegate> delegate; (類似于UITableView)
(BOOL)showsSelectionIndicator // 是否顯示選擇訓示器 ,即是一個藍色的條
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- 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];
以上可以在視圖顯示一個選取器,但是内容空白,pickerView.showsSelectionIndicator=YES;是這隻目前選取器所選中的内容:
選取器上顯示資料,必須依賴兩個協定,UIPickerViewDelegate和UIPickerViewDataSource,把他們添加到ViewController.h檔案中
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- #import <UIKit/UIKit.h>
- @interface ViewController : UIViewController<UIPickerViewDelegate,UIPickerViewDataSource>
- {
- UIPickerView *pickerView;
- NSArray *pickerData;
- }
- @end
3.然後在.m檔案的ViewDidLoad中初始化界面
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- - (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",@"周傑倫",@"梁靜茹",@"許飛",@"鳳凰傳奇",@"阿杜",@"方大同",@"林俊傑",@"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];
- }
4.實作UIPickerView的代理方法,将資料顯示在選取器上所需要幾個方法
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- #pragma mark -
- #pragma mark Picker Date Source Methods
- //傳回顯示的列數
- -(NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView
- {
- return 1;
- }
- //傳回目前列顯示的行數
- -(NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component
- {
- return [pickerData count];
- }
- #pragma mark Picker Delegate Methods
- //傳回目前行的内容,此處是将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];
- }
前兩個是資料源的代理方法,一個是傳回列,有幾個選取器就傳回幾,第二個是設定選取器有多少行,因為就這一個選取器,是以直接傳回行數,即數組元素個數多少;第三個代理方法是将數組元素添加到了選取器上面顯示 ;
說一下兩個協定執行個體方法,參考http://www.cnblogs.com/edsioon/
UIPickerViewDelegate中的執行個體方法
// 當使用者選擇某個row時
- (void) pickerView: (UIPickerView *)pickerView didSelectRow: (NSInteger)row inComponent: (NSInteger)component
// 當其在繪制row内容,需要row的高度時
- (CGFloat) pickerView:(UIPickerView *)pickerView rowHeightForComponent: (NSInteger) component
// 傳回指定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.傳回值為用作row内容的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
UIPickerViewDataSource中的執行個體方法
按照官方文檔的說法,UIPickerViewDataSource這個協定僅有的功能就是提供picker view中component的個數和各個component中的row的個數,雖然名為datasource,但是它工作于MVC的C中
本協定僅有兩個執行個體方法,均需要實作:
// 傳回列數
- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView
// 傳回每一列對應的行數
- (NSInteger) pickerView:(UIPickerView *) pickerView numberOfRowsInComponent:(NSInteger) component
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,
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- -(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];
- }
@UIPickerView還有其他執行個體方法
// 擷取指定列的行數
- (NSInteger) numberOfRowsInComponent:(NSInteger)component
// 重新整理所有的列
- (void) reloadAllComponents
// 重新整理指定的列
- (void) reloadComponent: (NSInteger) component
- (CGSize) rowSizeForComponent: (NSInteger) component
// 擷取某列選擇的行數
- (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
附上源代碼: http://download.csdn.net/detail/duxinfeng2010/4410909