variables declared in @implementation

Question

I'm working through a code listing from a book and it has a pair of variables (specifically NSString *) declared and initialised in the @implementation rather than the @interface but outside of any method body. I've not seen this before and I'm wondering what the difference this makes in scope and so on.

I've had a quick look in The Objective C Programming Language but I can't see anything describing what effect this has.

Thanks

Andy

will you post as code sample that shows what you're talking about? — kubi
– kubi, Commented Jun 17, 2010 at 12:42

Philippe Leybaert · Accepted Answer · 2010-06-17 12:43:22Z

8

Variables declared inside @implementation have global scope.

If you declare them as "static", they are only visible from the methods in the same source file.

So:

@implementation MyClass

NSString *myString; // global scope, and accessible by all code in your project

or

@implementation MyClass

static NSString *myString; // global scope, but only accessible by code 
                           // in this source file

answered Jun 17, 2010 at 12:43

Philippe Leybaert

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3 Comments

huggie Over a year ago

I was searching for answer and realized that if its in bracelet, then it's actually ivar. See stackoverflow.com/questions/6785765/…

atastrophic Over a year ago

are you sure about that ?? I can't make it work. Perhaps you made wrong comments

Nicolas Miari Over a year ago

What's the difference between defining them outside the @implementation block or inside it?

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