Question

Here’s what I’m trying to do:

I want to put away some methods into separate .h and .m files for a better overview of my code.

So basically I have the myViewController which I want to extend with the method myReactionOnAnimationDidEnd: as a category.

So I declared in "myCustomClasses.h" the following to extend it with my desired method:

#import "myViewController.h"
@interface myViewController (myReactionOnAnimationDidEnd)
- (void)myReactionOnAnimationDidEnd:(NSNotification *)aNotification;
@end

The implementation in "myCustomClasses.m" is:

#import "myCustomClasses.h"
#import "myViewController.h"

@implementation myViewController (myReactionOnAnimationDidEnd)    
- (void)myReactionOnAnimationDidEnd:(NSNotification *)aNotification {

    self.myLabel1.text = @"Test"; 
}
@end

The Compiler throws a build failed error “Cannot find interface declaration for ‘myViewController'”

So here’s my questions:

1. The first weird thing is, that everything works fine if I do exactly the same for UIViewController instead of myViewController. But since myViewController is a subclass of UIViewController, why shouldn’t it work for myViewController as well(@interface iSnahViewController : UIViewController)?

2. The other weird thing is that the @implementation in “myCustomClasses.m” works just fine if I skip on the @declaration completely. Now how can that be??

Thank you guys!
Any help much appreciated!!
Hans

---

Now, the funny thing is, that this very same building error comes up even if I create the category with the New File -> ObjC – Category Template. It basically creates the following two files:

in the header file:

#import "myViewController.h"

@interface myViewController (myCategories)  //<-- "Cannot find interface declaration for 'myViewController'"



@end

and with the .m file

#import "myViewController+myCategories.h"

@implementation myViewController (myCategories)


@end

And that’s already enough to bring up the error from above.

Answer 1

I finally got it working!

As the building error occured, I was importing the Category-.h File into the primery Class’s .h file:

#import "myViewController+myCategories.h" //<-- in the  "myViewController.h" 

which lead to the building error from above. This seems to be wrong! So don’t do that.

I still don’t fully understand how the “myViewController” Class gets to know about it’s categories without even having their .h files imported, but as this appears to be a working way of how this is done, I wanted to share with you.

Thanks everybody for helping!!