Swift Meta Type & .Self, & AnyClass

AnyClass

AnyClass is no more than a type alias about AnyObject.Type

typealias AnyClass = AnyObject.Type

Meta Type

Meta type in Swift is some of backbone of Swift typing system. We could use A.Type and A.self.

A.Type is equivalent to Type of Meta Type Instance and A.self is Meta Type Instance. So we can code like that.

let typeInt: Int.Type = Int.self

Usage of Meta Type

This utensil of type system allows us to call initializer of type like that.

let a = typeInt.init("1")

or call class or instance method of type

class A {
    required init() {}
    class func method() {
      print("Hello")
    }
    func method2() {
      print("Hello2")
    }
}

let typeA: A.Type = A.self
type.method()
typeA.method2(A())()
typeA.init() // needs required init
}

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References

ANYCLASS, META TYPE AND .SELF