SamStone92

employee.nextManagementLevel = boss
boss.nextManagementLevel = ceo

SamStone92

let employee = Employee()
let boss = Boss()
let ceo = CEO()

SamStone92

...

if expenditure.amount > 1001 && expenditure.amount < 10000 {
		print("The CEO can approve this expenditure")
} else {
		print("This expenditure is too large and won't get approved")
}

...

SamStone92

class Boss : Chain {
    
    private var _nextManagementLevel : Chain?
    var nextManagementLevel : Chain{
        set{
            _nextManagementLevel = newValue
        }
        get{
            return _nextManagementLevel!
        }

SamStone92

protocol Chain{
    
    var nextManagementLevel : Chain{ get set }
    func shouldApproveExpenditure(expenditure : Expenditure)

}

SamStone92

class Expenditure {
    
    private var _amount = Int()
    var amount : Int{
        get{
           return _amount
        }
        
        set {
            _amount = newValue

SamStone92

let subject = Subject()

let binary = BinaryObserver(subject: subject, id: 1)
let octal = OctalObserver(subject: subject, id: 2)
let hex = HexaObserver(subject: subject, id: 3)

subject.number = 15
subject.removeObserver(observer: binary)
subject.number = 2

SamStone92

func removeObserver(observer : Observer) {
    observerArray = observerArray.filter{ $0.id != observer.id }
}

SamStone92

let subject = Subject()

let binary = BinaryObserver(subject: subject, id: 1)
let octal = OctalObserver(subject: subject, id: 2)
let hex = HexaObserver(subject: subject, id: 3)

subject.number = 15
subject.number = 2

SamStone92

class BinaryObserver : Observer{
    
    private var subject = Subject()
    var id = Int()

    init(subject : Subject, id : Int) {
        self.subject = subject
        self.subject.attachObserver(observer: self)
        self.id = id
    }