andreaslydemann

let myOptional: Int? = 10

if let myInt = myOptional { 
  print("myInt has a value of \(myInt).")
}

andreaslydemann

let myOptional: Int? = nil

let myInt = myOptional ?? 0

print("myInt has a value of \(myInt).")

andreaslydemann

let myOptional: Int? = 10

print("myOptional has a value of \(myOptional!).")

andreaslydemann

let myOptional: Int? = 10

guard let myInt = myOptional else { 
  print("myInt has no value.")
}

print("myInt has a value of \(myInt).")

andreaslydemann

let myFirstOptional: Int? = 10
let mySecondOptional: Int? = 20

if let myFirstInt = myFirstOptional, let mySecondInt = mySecondOptional { 
  print("myFirstInt has a value of \(myFirstInt) and mySecondInt has a value of \(mySecondInt).")
}

andreaslydemann

struct Processor {
    var modelNumber: Int
    init() {
        self.modelNumber = 21043
    }
}

struct Computer {
    var processor: Processor?
    init(processor: Processor?) {

andreaslydemann

let center = NotificationCenter.default
center.addObserver(self, 
                   selector: #selector(onNotificationReceived(_:)), 
                   name: .notificationReceived, 
                   object: nil)

@objc func onNotificationReceived(_ notification:Notification) {
    if let data = notification.userInfo as? [String: Int] {
        // Do something with the data
    }

andreaslydemann

let center = NotificationCenter.default
let notificationReceived = Notification.Name("notificationReceived")
let pizzas = ["Margherita": 1, "Pepperoni": 16, "Hawaii": 25]

center.post(name: notificationReceived, object: self, userInfo: pizzas)

andreaslydemann

func post(name aName: Notification.Name, 
          object anObject: Any?, 
          userInfo aUserInfo: [AnyHashable : Any]? = nil)

andreaslydemann

func addObserver(_ observer: Any, 
                 selector aSelector: Selector, 
                 name aName: Notification.Name?, 
                 object anObject: Any?)