Optionals are enums. With case None, and case Some(T). <T> is just a generic. 

let x: String? = nil

is the same as 

let x = Optional<String>.None

let x: String? = “hello”

is the same as

let x = Optional<String>.Some(”hello”)

exclamation mark and question marks are syntactic sugar. 

Optionals can be “Chained”: 

if let x = display?.text?.hashValue {...}

chain the optionals. So if any of these are uninitialized, then the whole thing is just nil. 

There is also a default operator for optionals.