Swift: Optionals for Beginners

Alfie Hanssen raises a good point in his primer on Swift and optionals:

Swift Optionals allow this check (ensure a variable is something or nothing) to happen at compile-time. If we attempt to use an optional variable without unwrapping it, the compiler will throw an error instructing us to first unwrap the value. Which means that the compiler will never let us use an optional value without first being certain that it is something or nothing.”

Swift Tutorial: Optionals for Beginners