Swift Functional Programming - Second Edition

Implicitly-unwrapped optionals

We can define implicitly-unwrapped Optionals by appending an exclamation mark (!) to the end of the type. These types of Optionals will unwrap themselves.

The following example presents two ways to get a value from a dictionary. In the first example, the resulting value will be an optional so should be unwrapped. The second example will implicitly unwrap the value:

Like forcefully unwrapping, implicitly-unwrapped Optionals may cause runtime crashes in our applications, so we need to be cautious when we use them.