-(void)someMethod:(UIScrollView*)scrollView{
 [[NSNotificationCenter defaultCenter]
     addObserver:self
     selector:@selector(keyboardWasShown:)
     name:UIKeyboardDidShowNotification object:nil];
}
-(void)keyboardWasShown:(NSNotification *)aNotification{
// I want to get scrollView over here
}

[[NSNotificationCenter defaultCenter]
postNotificationName:UIKeyboardWillHideNotification
object:self
 userInfo:@{@"scrollView":scrollView}];

-(void)keyboardWasShown:(NSNotification *)aNotification{
    UIScrollView *scrollView = aNotification.userInfo[@"scrollView"];
}