Self in

About Self

Instances of structs and classes each have an implicit value named self which refers to the instance itself. There are multiple uses for self, but it is most commonly used to disambiguate the names of properties and methods of the struct/class when there may be some confusion.

struct MySelf {
  var x = 0

  mutating func move(x: Int) {
    // here if we just say x = x it is unclear if we mean
    // the property x or the method parameter x, so we use
    // self for clarity
    self.x = x
  }
}

Structs and classes also have a Self value which refers the type if the struct or class, rather than the instance of the struct or class.