Accessing category method in original Objective C class

Question

I have a class for which I have created a category. Now I want to access category method inside original class but I am getting error:

error: instance method '-hasSound' not found (return type defaults to 'id') [-Werror,-Wobjc-method-access]

// Animal.h 
@interface Animal: NSObject 
- (void)sound;
@end

// Animal.m
#import "Animal+Additions.h"
@implementation Animal
- (void)sound {
 [self hasSound];
}
@end

// Animal+Additions.h
@interface Animal (Additions) 
- (BOOL)hasSound;
@end

// Animal+Additions.h
@implementation Animal (Additions)
- (BOOL) hasSound {
   return YES;
}
@end

I have been doing same thing in Swift but not sure how to achieve the same thing in Objective C. Category and original class are in separate files. I have imported Category interface file inside original class but that didn't work.

Answer 1

You have not shown sufficient #import statements, so I have to assume they don't exist. You need them.

Another possible issue is that, at least according to your comments, you seem to have two Animal+Additions.h files but no Animal+Additions.m file.

This complete code in four files compiles for me:

//  Animal.h

#import <Foundation/Foundation.h>
@interface Animal: NSObject
- (void)sound;
@end

//  Animal.m

#import "Animal.h"
#import "Animal+Additions.h"
@implementation Animal
- (void)sound {
    [self hasSound];
}
@end

// Animal+Additions.h

#import "Animal.h"
@interface Animal (Additions)
- (BOOL)hasSound;
@end

//  Animal+Additions.m

#import "Animal+Additions.h"
@implementation Animal (Additions)
- (BOOL) hasSound {
    return YES;
}
@end

Note all the #import statements, and note that the Animal.m file must be part of the target.