ClassEquality.swift

import Foundation

class BaseClass : Equatable {
    var stringValue: String = ""
}


class SubClass : BaseClass {
    var intValue: Int = 0
}


func ==(lhs: BaseClass, rhs: BaseClass) -> Bool
{
    if lhs.stringValue == rhs.stringValue {
        return true
    } else {
        return false
    }
}


func ==(lhs: SubClass, rhs: SubClass) -> Bool
{
    if (lhs as BaseClass) == (rhs as BaseClass) &&
        lhs.intValue == rhs.intValue {
        return true
    } else {
        return false
    }
}


let a1 = BaseClass()
a1.stringValue = "Foo"

let a2 = BaseClass()
a2.stringValue = "Foo"
a1 == a2


let b1 = SubClass()
b1.stringValue = "Foo"
b1.intValue = 4

let b2 = SubClass()
b2.stringValue = "Foo"
b2.intValue = 2
b1 == b2


let c1: BaseClass = b1
let c2: BaseClass = b2
c1 == c2