I ran into the same problem using this PDF viewing code. I simply added this method
- (void)dismissReaderViewController:(ReaderViewController *) viewController
{
[self dismissModalViewControllerAnimated:YES];
}
to the .m file where I'm calling the - (IBAction)didClickOpen
from.
This is mainly due to the fact that in ReaderViewController.m the delegate expects to see dismissReaderViewController declared in your implementation file. Otherwise, it will throw that error you're getting.
Note: Use [self dismissViewControllerAnimated:YES completion:nil];
for iOS6 or later since dismissModalViewControllerAnimated:YES was deprecated :-)