One of the stated reasons that structs can be more performant than classes is that no ARC is needed for structs. But suppose we have the following struct in swift:struct Point {   var x:Float   var y:Float   mutating func scale(_ a:Float){      x *= a      y *= a   } }var p1 = Point(x:1, y:1)var p2 = p1 //p1 and p2 point to the same data internallyp1.scale(2) //copy on mutate, p1 and p2 now have distinct copiesNow I believe that various copies of a struct will actually point to the same data on the stack until a mutation forces a copy. This means either we have to keep track of how many objects reference a given memory address on the stack so we know if a mutation must form a copy, or we simply form a copy on every mutation. The former seems inefficient and the latter seems identical to ARC. What am I missing?EDIT: I understand the difference between value semantics and reference semantics. But as an optimization swift does not actually create a new copy of the data until a mutation is made. This avoids unnecessary copies. See https://www.hackingwithswift.com/example-code/language/what-is-copy-on-write . But because of this I am not sure how they can avoid some form of ARC. I noticed that this article claims that copy on write is only done for arrays and dictionaries. Not sure if that is true but if so then my questions still stands for arrays.
Struct vs class in Swift
optimization;swift language