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iOS Developer Interview Questions

When using arrays, what’s the difference between map() and compactMap()?

Suggested approach: Remember to give practical examples as well as outlining the core differences. So, you might start by saying the map() transforms a sequence using a function we specify, whereas compactMap() does that same step but then unwraps its optionals and discards any nil values. For example, converting an array of strings into integers works better with compactMap(), because creating an Int from a String is failable.

  Estimated difficulty: Easy

Important notes

  • There are over 150 interview questions in the system. Once you've read the question and come up with a suitable answer, try reading my suggested approach and see if it helps you add more detail.
  • These questions are not designed to be hard; a good interviewer is more interested in generating discussion that lets your ability and interests shine through.
  • If you answer a question with "yes" or "no" you've missed the point – interviewers prefer you to provide reasoning, explanation, or detail, so try to elaborate with examples!
  • If you're looking for detailed technical questions about the language, you should try my Swift tests instead – there are multiple challenges that will work your brain hard.
  • For a whole series of coding challenges, I wrote the perfect book for you: Swift Coding Challenges.

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See the full list of iOS interview questions

 
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