iPhone ModalViewController For Table View Open by Button?

Question

App Description: I have a UIWebview and a Toolbar beneath it. A button on the toolbar should bring up a modal table view, but it does not.

The toolbar has four buttons:

Previous: Goes to previous site

Next: Goes to the next site (these two being different than the default goForward and goBack methods)

Menu: Display a modalViewController with a TableView of all the available sites (sites will be limited to an array of site links that the next and previous buttons cycle through)

Refresh: Refreshes current site

Application has four main classes/files

WebAppDelegate.h and .m

ListViewController.h and .m (which has the Table View in its xib and the code to fill the table in the .m/ be the modal view controller)

There is only one warning and no errors.

Warning: 'WebAppDelegate' may not repsond to '-presentModalViewController:animated:'

When I run the program, everything is fine until I click the Menu button. I receive this runtime error

[WebAppDelegate presentModalViewController:animated:]: unrecognized selector sent to instance

Below is the code for the Menu button, which is currently in WebAppDelegate.m

-(IBAction)menu:(id)sender {
ListViewController *aListView=[[ListViewController alloc] initWithNibName:@"ListViewController" bundle:[NSBundle mainBundle]];
[self setListController:aListView];
aListView.modalTransitionStyle=UIModalTransitionStyleCoverVertical;
[self presentModalViewController:aListView animated:YES];
[aListView release];
}

Any ideas on what causes the application to crash and why the modal table view does not display?

Answer 1

The error message tells you exactly what your problem is - you're sending a selector to an object that doesn't respond to that selector.

[self presentModalViewController:aListView animated:YES];

self in this case in your instance of WebAppDelegate, which is probably a subclass of NSObject, not UIViewController. presentModalViewController:animated: is a method on UIViewController, so you need to send that message to whatever view controller is currently displayed (or perhaps a navigation controller) if you want to present another view controller modally.

Do not ignore compiler warnings - the one warning you have is likely telling you that...

'WebAppDelegate' may not respond to '-presentModalViewController:animated:'

...which, again, is exactly your problem.

Answer 2

[self.navigationController presentModalViewController:aListView animated:YES];