Optional chaining

Swift provides us with a shortcut when using optionals: if you want to access something like a.b.c and b is optional, you can write a question mark after it to enable optional chaining: a.b?.c.

When that code is run, Swift will check whether b has a value, and if it’s nil the rest of the line will be ignored – Swift will return nil immediately. But if it has a value, it will be unwrapped and execution will continue.

To try this out, here’s an array of names:

let names = ["John", "Paul", "George", "Ringo"]

We’re going to use the first property of that array, which will return the first name if there is one or nil if the array is empty. We can then call uppercased() on the result to make it an uppercase string:

let beatle = names.first?.uppercased()

That question mark is optional chaining – if first returns nil then Swift won’t try to uppercase it, and will set beatle to nil immediately.

SPONSORED Would you describe yourself as knowledgeable, but struggling when you have to come up with your own code? Fernando Olivares has a new book containing iOS rules you can immediately apply to your coding habits to see dramatic improvements, while also teaching applied programming fundamentals seen in refactored code from published apps.

Try the book!

Sponsor Hacking with Swift and reach the world's largest Swift community!