Swift Design Pattern. Why did they include Any, AnyObject

Question

I've recently moved to Swift from regular objc. And yes, I know how to use Any and AnyObject.

But I'm curious why Apple decided on AnyObject and Any. Why is it good? What problem is it solving? How much developer time is it saving?

Answer 1

For backward compatibility with existing Cocoa libraries. Classes like NSDictionary, NSArray, etc. do not enforce type on all objects contained. Also in Obj-C there's id which is a pointer to any Obj-C object.