Swift by example optionals 

import Foundation
As an alternative to multiple return values (Go)
Or Exceptions (every other language)
Optionals are used to handle failure cases when
you're good and ready. Sorta like a lightweight
Maybe monad, without the FP hoity-toity. 

var one = "1"
var intVal = Int(one)
Use a if-check to determine if there's an underlying value. 
if let intVal = Int(one) {
    // And then access the underlying value with !
    print(intVal)                                              // 1
}

var nope = "please"
var nopeIntVal = Int(nope)

if nopeIntVal == nil {
    print("Couldn't convert the string to an int")
}
Creating optionals. 
var maybe:String? = nil

print(maybe)                                                  // nil
print(maybe == nil)                                           // true

maybe = "yep"

print(maybe)                                                  // yep