UIPopoverController 使用

开发iPad应用程序与iPhone有一点小差别，就是iPad支持弹出框。这个示例展示如何在UIPopoverController上显示一个UIPickerView,当然你可以显示任何的UIView到UIPopover上面。原理就是构建一个UIViewController，然后将这个UIViewController加在UIPopoverController上，最近显示UIPopoverController，即显示出我们的UIViewController的内容。

首先，要我们的controller支持UIPickerViewDelegate，UIPopoverControllerDelegate协议，

@interface myViewController : UIViewController<UIPickerViewDelegate，UIPopoverControllerDelegate>

@interface myViewController : UIViewController<UIPickerViewDelegate，UIPopoverControllerDelegate>

然后开始显示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];
}

- (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];
}

注意内存管理，要释放UIPopoverController：

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

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

还有实现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;
}

- (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里的内容自行修改。

//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

系统优化的我一愣一愣的，原来是下面的优化规则

TodoViewController *contentViewController = [[TodoViewController alloc] init];

UINavigationController *navigationController = [[UINavigationController alloc] initWithRootViewController:contentViewController];

navigationController.contentSizeForViewInPopover = CGSizeMake(100, 100); //内容大小

    UIPopoverController *popover = [[UIPopoverController alloc] initWithContentViewController:navigationController];

popover.popoverContentSize = CGSizeMake(300, 300); //弹出窗口大小，如果屏幕画不下，会挤小的。这个值默认是320x1100

CGRect popoverRect = CGRectMake(200, 700, 10, 10);

[popover presentPopoverFromRect:popoverRect  //popoverRect的中心点是用来画箭头的，如果中心点如果出了屏幕，系统会优化到窗口边缘

inView:self.view //上面的矩形坐标是以这个view为参考的

  permittedArrowDirections:UIPopoverArrowDirectionDown  //箭头方向

  animated:YES];

[contentViewController release];

[navigationController release];

//最佳实践，使用哪个view做参考，就以哪个view的bounds送进去就好了，箭头自动指向这个view的中心