WWDC24 SALE: Save 50% on all my Swift books and bundles! >>

iOS Developer Interview Questions

What are opaque return types?

Suggested approach: Whenever you see some in a return type, it’s an opaque return type – when you want to specify that some kind of type will be returned, but you don’t want to say what.

It’s important that you try to explain the difference between an opaque return type and returning a protocol, because in the latter your returned value can be absolutely anything whereas in the former the compiler knows what data was actually returned even if you don’t get access to that.

For bonus points, talk about how SwiftUI uses @ViewBuilder to silently allow us to return different view types from a view body.

  Estimated difficulty: Advanced

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

Unknown user

You are not logged in

Log in or create account

Link copied to your pasteboard.