when button pressed or when view Disappear in swift

i have 3 view controller. first view controller has a button and second view controller has a button.

my third view controller has 2 buttons (button 1 and button 2) when the button of first view controller or second view controller pressed it shows the third view controller, i want to write a code that if first view controller button pressed or view disappear my third view controller button 1 hide else second view controller button pressed or view disappear my third view controller button 2 hide.

i tried many ways in swift but it doesn't work at all, can any help me with that please...