NEW: My new book Pro SwiftUI is out now – level up your SwiftUI skills today! >>

Wrap up

Coming into this project you might thought strings were trivial, but I hope I’ve shown you that there’s more to them than meets the eye.

We’ve looked at how strings are different from arrays, how we can write useful extensions for strings, how Swift lets us combine functions together beautifully, and how NSAttributedString lets us add formatting to strings.

Of course, we’ve only just scratched the surface of strings here, but the challenges below will encourage you to write some extensions of your own so you get a better feel for how it works.

Review what you learned

Anyone can sit through a tutorial, but it takes actual work to remember what was taught. It’s my job to make sure you take as much from these tutorials as possible, so I’ve prepared a short review to help you check your learning.

Click here to review what you learned in project 24.


One of the best ways to learn is to write your own code as often as possible, so here are three ways you should try your new knowledge to make sure you fully understand what’s going on:

  1. Create a String extension that adds a withPrefix() method. If the string already contains the prefix it should return itself; if it doesn’t contain the prefix, it should return itself with the prefix added. For example: "pet".withPrefix("car") should return “carpet”.
  2. Create a String extension that adds an isNumeric property that returns true if the string holds any sort of number. Tip: creating a Double from a String is a failable initializer.
  3. Create a String extension that adds a lines property that returns an array of all the lines in a string. So, “this\nis\na\ntest” should return an array with four elements.
Hacking with Swift is sponsored by Play

SPONSORED Play is the first native iOS design tool created for designers and engineers. You can install Play for iOS and iPad today and sign up to check out the Beta of our macOS app with SwiftUI code export. We're also hiring engineers!

Click to learn more about Play!

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

Share your success!

One of the most effective motivators of success is sharing your progress with other people – when you tell folks what you're doing and what you've learned, it encourages you to come back for more, which in turn will help you reach your app development goals faster.

So, now that you've done all the hard work it's time to share your success: tell folks that you've completed this project, either by clicking the button below to start composing a tweet, or by writing your own message from scratch. This will definitely encourage you to keep learning, but it will also help other folks discover my work – thank you!


About the author

Paul Hudson is the creator of Hacking with Swift, the most comprehensive series of Swift books in the world. He's also the editor of Swift Developer News, the maintainer of the Swift Knowledge Base, and a speaker at Swift events around the world. If you're curious you can learn more here.

Buy Pro Swift Buy Pro SwiftUI Buy Swift Design Patterns Buy Testing Swift Buy Hacking with iOS Buy Swift Coding Challenges Buy Swift on Sundays Volume One Buy Server-Side Swift Buy Advanced iOS Volume One Buy Advanced iOS Volume Two Buy Advanced iOS Volume Three Buy Hacking with watchOS Buy Hacking with tvOS Buy Hacking with macOS Buy Dive Into SpriteKit Buy Swift in Sixty Seconds Buy Objective-C for Swift Developers Buy Beyond Code

Was this page useful? Let us know!

Average rating: 5.0/5

Unknown user

You are not logged in

Log in or create account

Link copied to your pasteboard.