Unrecognized selector sent to instance - iphone

Question

Anyone know why I am getting this error?
Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[CustomRaisedTabViewController cancel:]: unrecognized selector sent to instance 0x4d321e0'
This is the code where it is failing. This is in my CustomTabViewController. The error is happening when I click my "Cancel" button.
-(IBAction)showPostModalViewController {
PostActionModalViewController *addController = [[PostActionModalViewController alloc]
initWithNibName:#"PostActionModalView" bundle:nil];
// Configure the PostAddViewController. In this case, it reports any
// changes to a custom delegate object.
addController.delegate = self;
// Create the navigation controller and present it modally.
UINavigationController *navigationController = [[UINavigationController alloc]
initWithRootViewController:addController];
[self presentModalViewController:navigationController animated:YES];
UIBarButtonItem *cancelButton =
[[UIBarButtonItem alloc] initWithTitle: #"Cancel"
style: UIBarButtonItemStylePlain
target: self
action: #selector(cancel:)];
addController.navigationItem.rightBarButtonItem = cancelButton;
[cancelButton release];
//[self presentModalViewController:addController animated:true];
[navigationController release];
[addController release];
}
-(IBAction)cancel {
[self.parentViewController dismissModalViewControllerAnimated:YES];
}

Answer 1

Because the cancel: method is not cancel which is what you've defined.
Change your cancel action to look like this:
- (IBAction)cancel:(id)sender {
...
}

Answer 2

action: #selector(cancel:)
For the action selector which takes parameter! cancel: that means which will take another parameter.
change your method to
-(IBAction)cancel:(id)sender{
// Do wat you want
}
or
-(IBAction)cancel:(UIButton *)btnSender{
/// Do what you want
}

Answer 3

you have to modify the cancel method signature in
-(IBAction)cancel:(id)sender
{
[self.parentViewController dismissModalViewControllerAnimated:YES];
}
when you added the action to your cancelButton (during initialization) you specified the "cancel:" selector, this means that it will be called a method having one parameter (the sender button)