Methods
Methods are functions that belong to a struct, class, or enum.
Instance methods
Instance methods belong to an instance of a struct, class, or enum. They may access the instance’s variables. Below are examples of an instance method intro():
Struct example
struct Person {
let name: String
init(name: String) {
self.name = name
}
func intro() {
print("I'm \(name).")
}
}
let amy = Person(name: "Amy")
amy.intro() // I'm Amy.
Class example
class Person {
let name: String
init(name: String) {
self.name = name
}
func intro() {
print("I'm \(name).")
}
}
let amy = Person(name: "Amy")
amy.intro() // I'm Amy.
Enum example
enum Beatle: String {
case john
case paul
case george
case ringo
func intro() {
print("I'm \(rawValue).")
}
}
let john = Beatle.john
john.intro() // I'm john.
Mutating instance methods
Because structs are value types, an instance method that modifies its instance must be marked as mutating:
struct Player {
var name: String
var level: Int
mutating func levelUp() {
level += 1
}
}
var player = Player(name: "Amy", level: 1)
player.levelUp()
print(player.level) // 2
Static/class methods
Static and class methods (also known as type methods) belong to a struct/class type itself, rather than an instance of a struct/class. They are declared with static for a struct or class for a class:
struct Person {
let name: String
init(name: String) {
self.name = name
}
static func intro() {
print("I'm a static method.")
}
}
Person.intro() // I'm a static method.
class Person {
let name: String
init(name: String) {
self.name = name
}
class func intro() {
print("I'm a class method.")
}
}
Person.intro() // I'm a class method.
