How to perform a click of UIButton in swift

I have a UIView with some UIbuttons in it, and I just want to click one of the buttons when switching to this view. The buttons are built in this view so you can't click it and then switch to this view. The button that needs to be clicked is depending on the last view.

For example: I enter number 3 on the last view, when switched to this view, it will have number 3 button selected and it will perform whatever action that clicking number 3 button will do. I need to do this in Swift for an iPhone app. Thank you so much!