Associated Objects—或者 Associative References,正如他们起初所被认识的那样—是Objective-C 2.0 runtime的特征,在OS X Snow Leopard(IOS 4)中被引进。具体指的就是
@interface NSObject (AssociatedObject)
@property (nonatomic, strong) id associatedObject;
@end
NSObject+AssociatedObject.m
@implementation NSObject (AssociatedObject)
@dynamic associatedObject;
- (void)setAssociatedObject:(id)object {
objc_setAssociatedObject(self, @selector(associatedObject), object, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}
- (id)associatedObject {
return objc_getAssociatedObject(self, @selector(associatedObject));
}