0-struct-vs-enum.swift

enum EnumStyle {
  case a
  case b
  var x: Int {
    switch self {
    case .a: 1
    case .b: 2
    }
  }
  var y: Int {
    switch self {
    case .a: 3
    case .b: 4
    }
  }
}

// versus

struct StructStyle {
  var x: Int
  var y: Int
  static let a = Foo(x: 1, y: 3)
  static let b = Foo(x: 2, y: 4)
}

1-add-property.diff

 enum EnumStyle {
   case a
   case b
   var x: Int {
     switch self {
     case .a: 1
     case .b: 2
     }
   }
   var y: Int {
     switch self {
     case .a: 3
     case .b: 4
     }
   }
+  var z: Int {
+    switch self {
+    case .a: 5
+    case .b: 6
+    }
+  }
 }
 
 // versus
 
 struct StructStyle {
   var x: Int
   var y: Int
+  var z: Int
-  static let a = Foo(x: 1, y: 3)
-  static let b = Foo(x: 2, y: 4)
+  static let a = Foo(x: 1, y: 3, z: 5)
+  static let b = Foo(x: 2, y: 4, z: 6)
 }

2-add-value.diff

 enum EnumStyle {
   case a
   case b
+  case c
   var x: Int {
     switch self {
     case .a: 1
     case .b: 2
+    case .c: 3
     }
   }
   var y: Int {
     switch self {
     case .a: 3
     case .b: 4
+    case .c: 5
     }
   }
 }
 
 // versus
 
 struct StructStyle {
   var x: Int
   var y: Int
   static let a = Foo(x: 1, y: 3)
   static let b = Foo(x: 2, y: 4)
+  static let c = Foo(x: 3, y: 5)
 }