Hello everyone. Because there is no "virtual" keyword I don't know that how can I create a subclass which has 2 methods with 2 rule for each one:

• First method:
  • If object was created from its own class, it has to call its own method.
  • If there is an upcasting, it has to call the base class's method
• Second method:
  • If object created from its own class, it has to call its own method.
  • If there is an upcasting, it has to call its own method again.

Let me explain with c# code

// <BEGIN_IMPORTANT_PART>
Console.WriteLine("From base_derived");
Base base_derived = new Derived();
base_derived.ifPolyCallBase(); // nonOverridedFromBase
base_derived.ifPolyCallDerived(); // overridedFromDerived
// <END_IMPORTANT_PART>

Console.WriteLine("\nFrom base");
Base @base = new Base();
@base.ifPolyCallBase(); // nonOverridedFromBase
@base.ifPolyCallDerived(); // overridedFromBase

Console.WriteLine("\nFrom derived");
Derived derived = new Derived();
derived.ifPolyCallBase(); // nonOverridedFromDerived
derived.ifPolyCallDerived(); // overridedFromDerived

class Base
{
    virtual public void ifPolyCallBase()
    {
        Console.WriteLine("nonOverridedFromBase");
    }
    virtual public void ifPolyCallDerived()
    {
        Console.WriteLine("overridedFromBase");
    }
}

class Derived : Base
{
    public void ifPolyCallBase()
    {
        Console.WriteLine("nonOverridedFromDerived");
    }
    override public void ifPolyCallDerived()
    {
        Console.WriteLine("overridedFromDerived");
    }
}

In swift when i use override it calls only derived method, we cannot use without override too, and i cannot delete the method too because of other functionalities as you see. So my questions are:

What is the equivalent code in swift (you can use protocol-struct instead of classes if it is preferable) If there is no "virtual" keyword, I think there is a good reason, could you explain why?

With closest swift code I tried to explain what I want. Is there any way to change first output without change other ones.

class Base {
    func ifPolyCallBase() {
        print("FromBase")
    }
    func ifPolyCallDerived() {
        print("FromBase")
    }
}

class Derived: Base {
    override func ifPolyCallBase() {
        print("FromDerived")
    }
    override func ifPolyCallDerived() {
        print("FromDerived")
    }
}

let base_derived: Base = Derived()
base_derived.ifPolyCallBase() // FromDerived (PROBLEM: But I want to see output "FromBase" without change other outputs)
base_derived.ifPolyCallDerived() // FromDerived

let base: Base = Base()
base.ifPolyCallBase() // FromBase
base.ifPolyCallDerived() // FromBase

let derived: Derived = Derived()
derived.ifPolyCallBase() // FromDerived
derived.ifPolyCallDerived() // FromDerived

Thanks!

Thank you for your answer