.Type

Under the hood AnyClass is

Basically where ever you see AnyClass, Any.Type, AnyObject.Type,its because it‘s in need of a type. A very very common place we see it is when we want to register a class for our tableView using register func.

_{If you are confused as to what does ‘Swift.‘ do then above,then see the comments from here}

The above Could have also been written as:

.self

Where is it used?

If you are writing/creating a function that accepts a type e.g. class, not an instance then to you would write T.Type as the type of the parameter. What it expects as a parameter can be: String.self, CustomTableView.self, someOtherClass.self.

In continuation of the tableView code:

Playground code:

Easy example

struct Something {

    var x = 5

}

let a = Something()

type(of:a) == Something.self // true

Hard example

class SomeBaseClass {

    class func printClassName() {

        print("SomeBaseClass")

    }

}

class SomeSubClass: SomeBaseClass {

    override class func printClassName() {

        print("SomeSubClass")

    }

}

let someInstance: SomeBaseClass = SomeSubClass()

/*                      |                |

                    compileTime       Runtime

                        |                | 

To extract,use:       .self          type(of)

  The compile-time type of someInstance is SomeBaseClass,

  and the runtime type of someInstance is SomeSubClass */

type(of: someInstance) == SomeSubClass.self // TRUE

type(of: someInstance) == SomeBaseClass.self // FALSE

I highly recommend to read Apple documentation on Types. Also see here

https://stackoverflow.com/questions/31438368/swift-whats-the-difference-between-Metatype-type-and-self