Swift Class vs Struct

Swift Class vs Struct

Choose value semantics (struct) for simple data and reference semantics (class) for shared identity, inheritance, or Objective-C interop.

Key Differences

• Copying: Structs copy on assignment and passing; classes pass references.
• Inheritance: Classes support inheritance; structs do not.
• Identity: Classes have identity semantics; structs compare by value (when Equatable).

Example

struct Point { var x: Int; var y: Int }
class Counter { var value = 0 }

var p1 = Point(x: 1, y: 2), p2 = p1 // copy
p2.x = 9 // p1.x remains 1

let c1 = Counter(), c2 = c1 // same instance
c2.value = 7 // c1.value is 7