SWIFT

nil coalescing swift

var a: Int? = nil

// The right operand will be used if the left operand
// evaluates to nil.
print(a ?? "a is nil") // Prints "a is nil"

Swift Nil-coalescing operator

var someValue:Int!
let defaultValue = 5
let unwrappedValue:Int = someValue ?? defaultValue
print(unwrappedValue)