account.swift

//: Playground - noun: a place where people can play

class Account: Hashable {
    var accountID: String = ""
    var hashValue: Int = 0
}

func ==(lhs: Account, rhs: Account) -> Bool {
    return lhs.accountID == rhs.accountID
}

class FooAccount: Account {
}

class BarAccount: Account {
}

let foo = FooAccount()
foo.accountID = "foo"
foo.hashValue = 1
let bar = BarAccount()
bar.accountID = "bar"
bar.hashValue = 2
var accounts = Set<Account>()
accounts.insert(foo)
accounts.insert(bar)