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iOS Developer Interview Questions

What is type erasure and when would you use it?

Suggested approach: Type erasure allows us to throw away some type information, for example to say that an array of strings is actually just AnySequence – it’s a sequence containing strings, but we don’t know exactly what kind of sequence.

This is particularly useful when types are long and complex, which is often the case with Combine. So, rather than having a return type that is 500 characters long, we can just say AnyPublisher<SomeType, Never> – it’s a publisher that will provide SomeType and never throw an error, but we don’t care exactly what publisher it is.

  Estimated difficulty: Advanced

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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