如何在catagory中添加属性

@interface NSObject (XY)

@property (nonatomic, strong) id tempObject;

@end

@implementation NSObject (XY)

@dynamic tempObject;

- (id)tempObject - {

id object = objc_getAssociatedObject(self, NSObject_key_tempObject);

return object;

}

 

- (void)setTempObject:(id)tempObject - {

[self willChangeValueForKey:@"tempObject"];

objc_setAssociatedObject(self, NSObject_key_tempObject, tempObject, OBJC_ASSOCIATION_RETAIN_NONATOMIC);

[self didChangeValueForKey:@"tempObject"];

}

@end