In Swift, it is possible to subclass a generic class. Suppose that we have a generic Container class. There are two different ways to subclass it. In our first example, GenericContainer subclasses the Container class and stays as a generic class. In our second example, SpecificContainer subclasses Container and becomes a Container of Int, therefore, it is not generic anymore:

class Container<Item> {
}

// GenericContainer stays generic
class GenericContainer<Item>: Container<Item> {
}

// SpecificContainer becomes a container of Int type
class SpecificContainer: Container<Int> {
}