UIViewController may not respond to showRootPopoverButtonItem - ios

Question

I am using Apple's MuiltipleDetailViewController sample app and get the message "UIViewController may not respond to showRootPopoverButtonItem"
This worked in XCode 3.X, but I get the message with 4.2
The app itself functions 100%, the popover is recognized in every nib, as is the table on the left when in landscape mode. But I can't submit with this warning. What do I need to change??
RootViewController.h
#import <UIKit/UIKit.h>
/*
SubstitutableDetailViewController defines the protocol that detail view controllers must adopt. The protocol specifies methods to hide and show the bar button item controlling the popover.
*/
#protocol SubstitutableDetailViewController <NSObject>
- (void)showRootPopoverButtonItem:(UIBarButtonItem *)barButtonItem;
- (void)invalidateRootPopoverButtonItem:(UIBarButtonItem *)barButtonItem;
#end
#interface RootViewController : UITableViewController <UISplitViewControllerDelegate> {
UISplitViewController *splitViewController;
UIPopoverController *popoverController;
UIBarButtonItem *rootPopoverButtonItem;
//UINavigationBar *navigationBar;
}
#property (nonatomic, assign) IBOutlet UISplitViewController *splitViewController;
#property (nonatomic, retain) UIPopoverController *popoverController;
#property (nonatomic, retain) UIBarButtonItem *rootPopoverButtonItem;
//#property (nonatomic, retain) IBOutlet UINavigationBar *navigationBar;
#end
RootViewController.m:
#import "RootViewController.h"
#import "WebViewController.h"
#import "Twitter.h"
//#import "SubstitutableDetailViewController.h"
#implementation RootViewController
#synthesize splitViewController, popoverController, rootPopoverButtonItem;//, navigationBar;
#pragma mark -
#pragma mark View lifecycle
- (void)viewDidLoad {
[super viewDidLoad];
// Set the content size for the popover: there are just two rows in the table view, so set to rowHeight*2.
self.contentSizeForViewInPopover = CGSizeMake(310.0, self.tableView.rowHeight*2.0);
//self.navigationController.navigationBar.tintColor = [UIColor colorWithRed:255/255 green:104/255 blue:1/255 alpha:1];
}
/*
-(void)customizeAppearance {
//create resizable images
UIImage *bluImage = [UIImage imageNamed:#"blu.jpg"];// resizableImageWithCapInsets:(0, 0, 0, 0)];
//set the bg for *all* UINavBars
[[UINavigationBar appearance] setBackgroundImage:bluImage forBarMetrics:UIBarMetricsDefault];
}
*/
-(void) viewDidUnload {
[super viewDidUnload];
self.splitViewController = nil;
self.rootPopoverButtonItem = nil;
}
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {
return YES;
}
- (void)splitViewController:(UISplitViewController*)svc willHideViewController:(UIViewController *)aViewController withBarButtonItem:(UIBarButtonItem*)barButtonItem
forPopoverController:(UIPopoverController*)pc {
// Keep references to the popover controller and the popover button, and tell the detail view controller to show the button.
barButtonItem.title = #"Index";
self.popoverController = pc;
self.rootPopoverButtonItem = barButtonItem;
UIViewController <SubstitutableDetailViewController> *detailViewController = [splitViewController.viewControllers objectAtIndex:1];
[detailViewController showRootPopoverButtonItem:rootPopoverButtonItem];
}
- (void)splitViewController:(UISplitViewController*)svc willShowViewController:(UIViewController *)aViewController
invalidatingBarButtonItem:(UIBarButtonItem *)barButtonItem {
// Nil out references to the popover controller and the popover button, and tell the detail view controller to hide the button.
UIViewController <SubstitutableDetailViewController> *detailViewController = [splitViewController.viewControllers objectAtIndex:1];
[detailViewController invalidateRootPopoverButtonItem:rootPopoverButtonItem];
self.popoverController = nil;
self.rootPopoverButtonItem = nil;
}
#pragma mark -
#pragma mark Table view data source
- (NSInteger)tableView:(UITableView *)aTableView numberOfRowsInSection:(NSInteger)section {
// Two sections, one for each detail view controller.
return 2;
}
- (UITableViewCell *)tableView:(UITableView *)aTableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = #"RootViewControllerCellIdentifier";
// Dequeue or create a cell of the appropriate type.
UITableViewCell *cell = [self.tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
//cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier] autorelease];
}
// Set appropriate labels for the cells.
if (indexPath.row == 0) {
cell.textLabel.text = #"Twitter";
}
else if (indexPath.row == 1) {
cell.textLabel.text = #"Contact Us";
}
cell.textLabel.textColor = [UIColor whiteColor];
cell.textLabel.backgroundColor = [UIColor blackColor];
cell.contentView.backgroundColor = [UIColor blackColor];
cell.detailTextLabel.backgroundColor = [UIColor blackColor];
return cell;
}
#pragma mark -
#pragma mark Table view selection
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
/*
Create and configure a new detail view controller appropriate for the selection.
*/
NSUInteger row = indexPath.row;
UIViewController *detailViewController = nil;
if (row == 0) {
Twitter *newDetailViewController = [[Twitter alloc]
initWithNibName:#"Twitter"
bundle:nil];
detailViewController = newDetailViewController;
}
if (row == 1) {
WebViewController *newDetailViewController = [[WebViewController alloc]
initWithNibName:#"WebViewController"
bundle:nil];
newDetailViewController.detailURL=
[[NSURL alloc] initWithString:#"http://www.chipmunkmobile.com/contact.html"];
detailViewController = newDetailViewController;
}
// Update the split view controller's view controllers array.
NSArray *viewControllers = [[NSArray alloc] initWithObjects:self.navigationController, detailViewController, nil];
splitViewController.viewControllers = viewControllers;
[viewControllers release];
// Dismiss the popover if it's present.
if (popoverController != nil) {
[popoverController dismissPopoverAnimated:YES];
}
// Configure the new view controller's popover button (after the view has been displayed and its toolbar/navigation bar has been created).
if (rootPopoverButtonItem != nil) {
[detailViewController showRootPopoverButtonItem:self.rootPopoverButtonItem];
}
[detailViewController release];
}
#pragma mark -
#pragma mark Managing the popover
/*
- (void)showRootPopoverButtonItem:(UIBarButtonItem *)barButtonItem {
// Add the popover button to the left navigation item.
[navigationBar.topItem setLeftBarButtonItem:barButtonItem animated:NO];
}
- (void)invalidateRootPopoverButtonItem:(UIBarButtonItem *)barButtonItem {
// Remove the popover button.
[navigationBar.topItem setLeftBarButtonItem:nil animated:NO];
}
*/
#pragma mark -
#pragma mark Memory management
- (void)dealloc {
[popoverController release];
[rootPopoverButtonItem release];
[super dealloc];
}
#end
Here is an image of the exact line where I get the warning

Answer 1

The reason you getting this warning is because of this UIViewController *detailViewController UIViewController does not have a method called "showRootPopoverButtonItem". If you want to get rid of the warning just do this instead:
[(WebViewController*)detailViewController showRootPopoverButtonItem:self.rootPopoverButtonItem];
or
[(Twitter*)detailViewController showRootPopoverButtonItem:self.rootPopoverButtonItem];
You just need to let it know its not really just a viewController, its a subclassed viewController you created. So what ever class showRootPopoverButtonItem: is in you just need to type cast it.

Answer 2

If you want to leave your code exactly the same but get rid of the warning you can do this.
if (rootPopoverButtonItem != nil) {
[detailViewController performSelector:#selector(showRootPopoverButtonItem:) withObject:self.rootPopoverButtonItem];
}
If you want to be more careful you should use this.
if (rootPopoverButtonItem != nil && [detailViewController respondsToSelector:#selector(showRootPopoverButtonItem:)]) {
[detailViewController performSelector:#selector(showRootPopoverButtonItem:) withObject:self.rootPopoverButtonItem];
}
Update
After reading through your code you could just specify the delegate on the detailViewController like you did in the other functions.
UIViewController<SubstitutableDetailViewController> *detailViewController = nil;
if (row == 0) {
//...

Answer 3

(1)Specify the Type for the detailedViewController: [(TYPE *)OBJECTNAME...
(2) Then Specify method call [(TYPE *)OBJECTNAME METHODCALL];
(*) You get the warning because the compiler does not know what type of object you are using. If you subclass a UIViewController then you have to specify type when accessing methods.Make sure the method is in .h so that you can access it.