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iOS Developer Interview Questions

What does the #error compiler directive do?

Suggested approach: Answering this isn’t hard (“it forces the compiler to emit an error using a message we specify”), but please make sure you follow up with at least one example. So, maybe you’re shipping some sample code where users need to enter an API key otherwise it won’t work, so you use #error next to the API key line saying “fill in your API key before continuing.” Similarly, you might use #error alongside an OS check to say that your code isn’t compatible with tvOS, for example.

  Estimated difficulty: Easy

See the full list of iOS interview questions

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.

Related questions

See the full list of iOS interview questions

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