Properties
Properties are variables or constants that belong to a struct, class, or enum. Properties can belong either to an instance or a type.
Instance properties
Instance properties are variables or constants that belong to an instance of a struct, class, or enum. Example:
struct Person {
let name: String
}
let person = Person(name: "Amy")
print("person's stored property 'name' is \(person.name)") // person's stored property 'name' is Amy
A stored property can have an initial value and change over time:
struct Person {
var name: String = "No Name"
}
var person = Person()
print(person.name) // No Name
person.name = "Amy"
print(person.name) // Amy
If a stored property is of an optional type, the default value is nil:
struct Person {
var name: String?
}
var person = Person()
print(person.name) // nil
Static/class properties
Static and class properties (also known as type properties) belong to a struct/class type itself, rather than an instance of a struct/class. If a type property is a stored property, it must have an initial value. They are declared with static:
struct Person {
static let greeting = "Hello"
let name: String
init(name: String) {
self.name = name
}
}
print(Person.greeting) // Hello
class Person {
static let greeting = "Hello"
let name: String
init(name: String) {
self.name = name
}
}
print(Person.greeting) // Hello
Computed properties
Computed properties are variables that are computed instead of holding a stored value. See Variables § Computed variables (get and set) for more information.
