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Checkpoint 2

Paul Hudson    @twostraws   

Updated for Xcode 14.2

Now that you’ve met arrays, dictionaries, and sets, I want to pause for a moment to give you chance to solve a small coding challenge. It’s not designed to trip you up, but instead to encourage you to stop for a while and think about what you’ve learned.

This time the challenge is to create an array of strings, then write some code that prints the number of items in the array and also the number of unique items in the array.

I’ll provide some hints below, but please take the time to think about a solution before you read them. Trust me: forgetting what you’ve learned then re-learning it actually makes it sink in deeper!

Hacking with Swift+ subscribers can get a complete video solution for this checkpoint here: Solution to Checkpoint 2. If you don’t already subscribe, you can start a free trial today.

Still here? Okay, here are some hints:

  1. You should start by creating an array of strings, using something like let albums = ["Red", "Fearless"]
  2. You can read the number of items in your array using albums.count.
  3. count also exists for sets.
  4. Sets can be made from arrays using Set(someArray)
  5. Sets never include duplicates.
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