Random spawn on screen

you could either do it in a while loop where you check with physics2d overlapsphere for example, but that could lead to an infinite loop if theres not space left. Or you can pregenerate a 2dimensional array of positions that span the whole screen, offset each of them by a small random amount and check this array for valid positions; modifications could be skipping indices into this array by a certain amount (wrapping at end) and stopping after a certain number of checks.