Add a variable to a class instance at runtime: Difference between revisions

NSLog(@"associatedObject: %@", associatedObject);

[e release];

[pool drain];

return 0;

}</lang>

You can also use a selector as the key, since two selectors with the same content are guaranteed to be equal:

<lang objc>#import <Foundation/Foundation.h>

#import <objc/runtime.h>

int main (int argc, const char *argv[]) {

NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];

id e = [[NSObject alloc] init];

// set

objc_setAssociatedObject(e, @selector(foo), [NSNumber numberWithInt:1], OBJC_ASSOCIATION_RETAIN);

// get

NSNumber *associatedObject = objc_getAssociatedObject(e, @selector(foo));