无法以编程方式显示 UIPopover

Question

我希望当应用程序首次以纵向模式启动时弹出窗口出现，而不是隐藏它并要求用户在弹出窗口出现之前点击按钮。我尝试通过 Google 和其他 StackOverflow 线程寻找解决方案，但我一直无法弄清楚。因此，如果 XCode 创建的标准 SplitView 示例不同，我会将代码放在下面。如果我能让它在这个应用程序上运行，我希望我能理解它并能够将它应用到其他地方。

我想过尝试在按下按钮时调用所调用的内容...但我不知道调用了什么以及在哪里声明它...我觉得我忽略了一些基本的东西，这让我发疯！

详细视图控制器 DetailViewController.h

#import <UIKit/UIKit.h>

@interface DetailViewController : UIViewController <UIPopoverControllerDelegate, UISplitViewControllerDelegate> {

UIPopoverController *popoverController;
UIToolbar *toolbar;

id detailItem;
UILabel *detailDescriptionLabel;
}

@property (nonatomic, retain) IBOutlet UIToolbar *toolbar;

@property (nonatomic, retain) id detailItem;
@property (nonatomic, retain) IBOutlet UILabel *detailDescriptionLabel;

@end

DetailViewController.m

#import "DetailViewController.h"
#import "RootViewController.h"


@interface DetailViewController ()
@property (nonatomic, retain) UIPopoverController *popoverController;
- (void)configureView; 
@end



@implementation DetailViewController

@synthesize toolbar, popoverController, detailItem, detailDescriptionLabel;

#pragma mark -
#pragma mark Managing the detail item

/*
 When setting the detail item, update the view and dismiss the popover controller if             it's showing.
 */
- (void)setDetailItem:(id)newDetailItem {
    if (detailItem != newDetailItem) {
        [detailItem release];
        detailItem = [newDetailItem retain];

        // Update the view.
        [self configureView];
    }

    if (self.popoverController != nil) {
        [self.popoverController dismissPopoverAnimated:YES];
    }        
}


- (void)configureView {
    // Update the user interface for the detail item.
    detailDescriptionLabel.text = [detailItem description];   
}


#pragma mark -
#pragma mark Split view support

- (void)splitViewController: (UISplitViewController*)svc willHideViewController:(UIViewController *)aViewController withBarButtonItem:(UIBarButtonItem*)barButtonItem forPopoverController: (UIPopoverController*)pc {

barButtonItem.title = @"Root List";
NSMutableArray *items = [[toolbar items] mutableCopy];
[items insertObject:barButtonItem atIndex:0];
[toolbar setItems:items animated:YES];
[items release];
self.popoverController = pc;
}


// Called when the view is shown again in the split view, invalidating the button and popover controller.
- (void)splitViewController: (UISplitViewController*)svc willShowViewController:(UIViewController *)aViewController invalidatingBarButtonItem:(UIBarButtonItem *)barButtonItem {

NSMutableArray *items = [[toolbar items] mutableCopy];
[items removeObjectAtIndex:0];
[toolbar setItems:items animated:YES];
[items release];
self.popoverController = nil;
}


#pragma mark -
#pragma mark Rotation support

// Ensure that the view controller supports rotation and that the split view can therefore show in both portrait and landscape.
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {
return YES;
}


#pragma mark -
#pragma mark View lifecycle

/*
// Implement viewDidLoad to do additional setup after loading the view, typically from a nib.
- (void)viewDidLoad {
[super viewDidLoad];
}
*/

/*
- (void)viewWillAppear:(BOOL)animated {
[super viewWillAppear:animated];
}
*/
/*
- (void)viewDidAppear:(BOOL)animated {
 [super viewDidAppear:animated]; 
}
*/
/*
- (void)viewWillDisappear:(BOOL)animated {
[super viewWillDisappear:animated];
}
*/
/*
- (void)viewDidDisappear:(BOOL)animated {
[super viewDidDisappear:animated];
}
*/

- (void)viewDidUnload {
// Release any retained subviews of the main view.
// e.g. self.myOutlet = nil;
self.popoverController = nil;
}


#pragma mark -
#pragma mark Memory management

/*
- (void)didReceiveMemoryWarning {
// Releases the view if it doesn't have a superview.
[super didReceiveMemoryWarning];

// Release any cached data, images, etc that aren't in use.
}
*/

- (void)dealloc {
[popoverController release];
[toolbar release];

[detailItem release];
[detailDescriptionLabel release];
[super dealloc];
}

@end

rootview 是一个典型的 UITableViewController，没什么特别的，但是如果出于某种原因你需要它或委托（这非常无聊，不加载视图）来帮助我解决这个问题，我发布这些也没有问题。同样，当我告诉 XCode 我想为 iPad 创建分割视图并且我没有修改它时，这就是 XCode 直接生成的结果。

希望我忽略了一些非常小的事情，它会让我拍着我的头说：“我不敢相信我错过了！”感谢您的帮助。

Answer 1

想通了！

我放入

[self.popoverController presentPopoverFromBarButtonItem:[[toolbar items] objectAtIndex:0] permittedArrowDirections:UIPopoverArrowDirectionUp animated:YES];

了ViewDidLoad方法。我知道这很简单！看起来工作没有任何问题！