How to use Button.onClick?

Hi, I am making a few automatically generated buttons for like a menu for 5 building blocks but I’ve looked everywhere to find how to use the Button.onClick and couldn’t find one working.

for(int i=0; i < 4; i++){
   Button buttonTrigger = newButton.GetComponent<Button>();
   buttonTrigger.onClick.AddListener(() => UI_ButtonSelect(i));
}

void UI_ButtonSelect(int index){
   //select block and hide menu
}

I’ve found and tried this but the buttons won’t work and there were no onClick functions in the inspector.

For some reason. This code was work for me long time ago

buttonTrigger.onClick.AddListener(() => UI_ButtonSelect(i));

But it not work anymore since I’m upgrade to unity 5

But instead. This code was work for me. But it not show on inspector

buttonTrigger.onClick.AddListener(delegate { UI_ButtonSelect(i);});