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iOS Developer Interview Questions

What steps do you take to identify and resolve performance issues?

Suggested approach: This is a tricky question to answer because “performance” has many forms, so be prepared to adjust your answer as you talk based on interviewer feedback.

If they mean graphical performance then you should probably talk about using the Core Animation instrument to identify slow drawing, but you should also consider venturing into the cost of Auto Layout in things like table view cells where lots of work happens quickly.

If they mean code performance then perhaps talk about stack traces, retain cycles, unnecessary caches, and similar – again make sure and bring Instruments in.

And then there's network performance, where you might talk about things such as batching requests to reduce battery wastage or using compression to save bandwidth.

  Estimated difficulty: Advanced

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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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