Your function does not return anything (String, String) -> Void, and your code contains:
return (inside1.center.x, inside1.center.y)
Which means it should return a tuple.
Based on your situation, either remove that return statement, or change your function's declaration to be (String, String) -> (Int, Int) or (String, String) -> (Float, Float) (or whatever you want the tuple parameters types to be).
