What data class is used to store elements in standard collections?

In standard iOS collections (such as NSArray, NSDictionary, NSSet), the classes NSObject or its subclasses are used to store elements. This means that collections store objects that inherit from NSObject, ensuring compatibility with the system and Objective-C runtime capabilities.

In Swift, standard collections (Array, Dictionary, Set) are generic and can store elements of any type, but under the hood, objects inheriting from NSObject are often used for interaction with Objective-C.