How can I override a function with various inherited arguments (Swift) - swift

Question

How to override a function with an inherited argument in Swift?
I have classes:
class ItemA {
var valueA: String?
func setValueA(_ value: String?) {
valueA = value
}
}
class ItemB: ItemA {
var valueB: String?
func setValueB(_ value: String?) {
valueB = value
}
}
// Analog of the abstract class
class ClassA {
func setValues(_ item: ItemA) {
item.setValueA("valueA")
getValues(item) // call getValues from ClassB
}
func getValues(_ item: ItemA) {
abort()
}
}
class ClassB: ClassA {
override func setValues(_ item: ItemB) { // item have type itemB, but extends ItemA
item.setValueB("valueB")
super.setValues(item)
}
override func getValues(_ item: ItemA) {
let item = item as! ItemB
let array = [item.valueA, item.valueB]
print(array)
}
}
My goal is to get the following results:
let itemB = ItemB()
ClassB().setValues(itemB)
// print ["valueA", "valueB"]
I can't override the function in the class because the types are different and there is no type inheritance in Swift. I get this error in setValues(_ item: ItemB) method from ClassB:
Method does not override any method from its superclass
In Java, this can be implemented using an abstract class and an extensible type:
abstract class ClassA {
<T extends ItemA> void setValues(T item) {
item.setValueA("valueA");
getValues(item);
}
abstract void getValues(MainItem item);
}

Answer 1

Correct answer depends on generics:
class ItemA {
var valueA: String?
func setValueA(_ value: String?) {
valueA = value
}
}
class ItemB: ItemA {
var valueB: String?
func setValueB(_ value: String?) {
valueB = value
}
}
// Analog of the abstract class
class ClassA {
func setValues<T : ItemA>(_ item: T) {
item.setValueA("valueA")
getValues(item) // call getValues from ClassB
}
func getValues(_ item: ItemA) {
abort()
}
}
class ClassB: ClassA {
override func setValues<T : ItemB>(_ item: T) {
// item have type itemB, but extends ItemA
item.setValueB("valueB")
super.setValues(item)
}
override func getValues(_ item: ItemA) {
let item = item as! ItemB
let array = [item.valueA, item.valueB]
print(array)
}
}
Check it! If you want to print non-optional values, unwrap them.
let itemB = ItemB()
ClassB().setValues(itemB)
// print ["valueA", "valueB"]

Answer 2

ClassB.setValues can't accept an argument of type ItemB (even though it's a subclass of ItemA), because doing so would violate the Liskov substitution principle.
ClassB instances need to be able to do anything that ClassA instances can. One such requirement is to accept ItemA arguments to its setValues method. Otherwise, what would happen in this code?
let classAInst: ClassA = ClassB()
classAInstance.setValues(ItemA())