I have 1 scrollview that contain 18 buttons. 1) when a user taps on any button, a button is added to a second UIScrollView. 2) Then, when a user taps on that button on second scrollview the button is removed from second scrollview. both uiscrollviews contain a list of their buttons. Afree both of these steps, I have to reload my scrollview. Can I do the same task by adding observer, so that it will automatically reload when any action done on button, and if yes then how?