Swift

6.5    Summary

In this chapter, you learned about optionals—a staple of Swift in terms of type safety. It is possible to mark a variable as optional, allowing it to carry nil values. When it comes to accessing an optional, Swift empowers programmers with easy syntax options while preserving safety—such as the nil-coalescing operator, optional binding, and optional chaining.

It is also possible to implicitly unwrap an optional, enforcing the unsafe assumption that it contains a value—but this technique should be avoided whenever possible.

So far, you’ve used variables as data holders. Simple variables, collections, and optionals: All of them hold data but don’t have any behavior. You have mostly used functions to implement behaviors in the program. ...