NEW! Master Swift design patterns with my latest book! >>

< Previous: Nil coalescing   Next: Optional try >

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.

Test your Swift today

Think you know Swift? My book Swift Coding Challenges will put your Swift skills to the test – it's perfect for job interviews and more!

< Previous: Nil coalescing   Next: Optional try >
MASTER SWIFT NOW
Buy Practical iOS 12 Buy Pro Swift Buy Swift Design Patterns Buy Practical iOS 11 Buy Swift Coding Challenges Buy Server-Side Swift (Vapor Edition) Buy Server-Side Swift (Kitura Edition) Buy Hacking with macOS Buy Advanced iOS Volume One Buy Hacking with watchOS Buy Hacking with tvOS Buy Hacking with Swift Buy Dive Into SpriteKit Buy Swift in Sixty Seconds Buy Objective-C for Swift Developers Buy Beyond Code

Was this page useful? Let me know!

Click here to visit the Hacking with Swift store >>