CODEWITHSUNDEEP
iphoneobjective-ciosobjective-c-category
pasawaya
pasawaya

Reputation: 11595

Extensions/Categories instead of Interface

So I noticed that in my new Xcode projects, by default there was a category for my class in my .m file. For example, I'll have this in the .m file:

@interface ViewController ()

@end

@implementation

   //Some code    

@end

I was wondering is it okay to declare my variables and functions in the category in the .m file, or should I do that in the .h file like before. Basically, what are the best practices in respect to categories.

By the way, my question is sort of related to the below link, but that link does not completely answer my question.

Upvotes: 2

Views: 437

Answers (1)

Sergey Kalinichenko
Sergey Kalinichenko

Reputation: 726639

This is not a category, it is a class extension (notice the empty parentheses). You can keep private implementation details, including private ivars, in the extension to limit the declarations in the .h file to the interface of your class. Note that you can add ivars only in the extensions, not in categories.

One very important consequence of this approach is that if you need ivars of types that require additional headers needed only for implementation, you can avoid including that header in the header of your interface, hiding implementation dependencies from users of your class.

Upvotes: 6

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