Type Properties

Type properties are properties on the type itself, not on the instance. They can be both stored or computed properties. You declare a type property with static:

struct Dog {
    static var noise = "Bark!"
}

print(Dog.noise) // Prints "Bark!"

In a class, you can use the class keyword instead of static to make it overridable. However, you can only apply this on computed properties:

class Animal {
    class var noise: String {
        return "Animal noise!"
    }
}
class Pig: Animal {
    override class var noise: String {
        return "Oink oink!"
    }
}

This is used often with the singleton pattern.