josh-marasigan

// This is an optional value
var box : String?

// This is an optional value set to an actual value
var box : String? = "Something"

josh-marasigan

var box: String?
print(box!)

josh-marasigan

var box: String? = "Something"
>>>
print(box!)
---
"Something"

var box: String?
>>>
print(box!)
---

josh-marasigan

// Ran in the same codeblock
var box1: String?
if let boxContents = box1 {
  print(boxContents)
}
---
Nothing Prints

var box2: String? = "Something"
if let boxContents = box2 {

josh-marasigan

// Within a function
var box: String? = "Something"
guard let boxContents = box else { return }
print(boxContents)
---
"Something"

josh-marasigan

class Mom {
  var _son: Son
  
  init(son: Son) {
    self._son = son
  }
  
  func tellJoshWhatToDo() {
    self._son.washDishes()
    self._son.cleanRoom()

josh-marasigan

protocol MomDelegate {
  func washDishes()
  func cleanRoom()
  func walkNala()
}

josh-marasigan

class Son: MomDelegate {

  func washDishes() {
    print("Washing Dishes")
  }
  
  func cleanRoom() {
    print("Cleaning Room")
  }
  

josh-marasigan

let josh = Son()
let joshsMom = Mom(son: josh)
joshsMom.tellJoshWhatToDo()
---
"Washing Dishes"
"Cleaning Room"
"Walking Nala"

josh-marasigan

// Most verbose: No compiler assumptions are made, the closure to map
// receives a transforming function explicitly casted as (val: Int) -> Int
// Transforms an array of Int and multiplies each value by 10 
arrValues.map({ (val: Int) -> Int in 
               return val * 10 
              })

// Compiler assumes return type for closure, no need to explicitly indicate
arrValues.map({ (val: Int) in 
               return val * 10