how to make an object visible again in game maker

Question

Fist of all, I'm really sorry for my bad English and I pretty new to game maker .

I have 2 object in the game : obj_apple and obj_door( I unchecked visible box) my question is how can I make an obj_door visible in the room when all the obj_apple are destroyed?

Answer 1

Object obj_door, Step event, place code (Add event -> Step -> Step -> tab Control -> section Code, first icon (Execute code)):

if !instance_exists(obj_apple) visible = true;

Answer 2

Another option, so you aren't making a check in every step event, is to put the check for the number of obj_apple in the destroy event of obj_apple.

For example, in the destroy event of obj_apple you would have:

if (instance_number(object_index) == 0) {
   with (obj_door) {
      visible = true;
   }
}