Unity2d : Spawning in Prefabs

My question is how to randomly spawn in objects on the screen with out them spawning in over each other? and if there is no room to spawn, then they wont spawn, and will wait in line or get canceled preferably?

Hiiā€¦

If you have specified location than you can arrange object at those location and make array of that gameobjects.and randomly active deactive those object from the array.