I want to pass 2 variables: UIImage * img int i into another method that only takes a (void *) I tried making a C struct containing both img and i struct MyStruct { UIImage *img; int i; } but xcode gives me an error saying "ARC forbids Objective-C objects in structs or unions" The next thing I tried is to write an objective-c class MyStruct2 containing img and i, alloc-initing an instance of it and typecasting it as (__bridge void*) before passing it to the method. Seems little involved for my use case. Seems like there should be a better way. What's the simplest way to achieve this? Thank you. Edit based on comments: I have to use void * as it is required by the UIView API. I created a selector as mentioned by UIVIew API + (void)setAnimationDidStopSelector:(SEL)selector Please see documentation for setAnimationDidStopSelector at http://developer.apple.com/library/ios/#documentation/uikit/reference/UIView_Class/UIView/UIView.html . It says ... The selector should be of the form: - (void)animationDidStop:(NSString *)animationID finished:(NSNumber *)finished context:(void *)context I want to pass both img and i into the (void *)context argument.