UIPickerView在UIPopoverController中正確顯示方法

開發iPad應用程式與iPhone有一點小差別，就是iPad支援彈出框。這個樣本展示如何在UIPopoverController上顯示一個UIPickerView,當然你可以顯示任何的UIView到UIPopover上面。原理就是構建一個UIViewController，然後將這個UIViewController加在UIPopoverController上，最近顯示UIPopoverController，即顯示出我們的UIViewController的內容。

首先，要我們的controller支援UIPickerViewDelegate，UIPopoverControllerDelegate協議，

@interface myViewController : UIViewController<UIPickerViewDelegate，UIPopoverControllerDelegate>

然後開始顯示uipickerview

- (void)showPickerInPopover:(CGRect)rect{UIViewController *sortViewController = [[UIViewController alloc] init];UIView *theView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 320, 216)];UIPickerView *thePicker = [[UIPickerView alloc] initWithFrame:CGRectMake(0, 0, 320, 216)];thePicker.delegate = self;thePicker.dataSource = self;thePicker.showsSelectionIndicator = YES;[theView addSubview:thePicker];sortViewController.view = theView;[theView release];        popViewController = [[UIPopoverController alloc] initWithContentViewController:sortViewController];[popViewController setPopoverContentSize:CGSizeMake(320, 216) animated:NO];    [popViewController presentPopoverFromRect:rect inView:self.view permittedArrowDirections:UIPopoverArrowDirectionAny animated:YES];popViewController.delegate = self;;    [sortViewController release];}

注意記憶體管理，要釋放UIPopoverController：

- (void)popoverControllerDidDismissPopover:(UIPopoverController *)popoverController{[popViewController release];}

還有實現UIPickerDelegate

- (void)pickerView:(UIPickerView *)pickerView didSelectRow: (NSInteger)row inComponent:(NSInteger)component {    // Handle the selection} // tell the picker how many rows are available for a given component- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component {    NSUInteger numRows = 5;     return numRows;} // tell the picker how many components it will have- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView { return 1;} // tell the picker the title for a given component- (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component {    NSString *title;    title = [@"" stringByAppendingFormat:@"%d",row];     return title;} // tell the picker the width of each row for a given component- (CGFloat)pickerView:(UIPickerView *)pickerView widthForComponent:(NSInteger)component { int sectionWidth = 300;  return sectionWidth;}

UIPickerView裡的內容自行修改。