BKInject
BKInject is a project to inject blocks before and after a method executes to help in debugging applications. In general, it's a bad idea to use this for anything else.
Usage
The usage is pretty simple:
[UIView bk_injectMethod:@selector(willMoveToSuperview:) before:^(NSInvocation *invocation) {
UIView *superview = nil;
[invocation getArgument:&superview atIndex:2];
NSLog(@"%@ moving to superview %@", invocation.target, superview);
} after:^(NSInvocation *invocation) {
}];