struct Point { var x: Int; var y: Int } var p1 = Point(x: 1, y: 2) var p2 = p1 // copy (value type) p2.x = 10 print(p1.x) print(p2.x) class Counter { var value = 0 } let c1 = Counter() let c2 = c1 // reference type c2.value = 5 print(c1.value)