Live coding

Swift Interview Copilot

Swift interviews pair a language round with a memory-management question that has ended more iOS loops than any algorithm ever has.

The round

What a Swift interview actually looks like

An iOS loop usually runs one coding problem in Swift, one question about ARC, and one about value semantics. The ARC question is rarely phrased as one: it arrives as a closure capturing self inside a view controller, and you are asked what happens next. Concurrency questions increasingly use async/await and actors rather than dispatch queues, and the follow-up asks which work belongs on the main actor — a question about correctness, since the wrong answer is a UI update off the main thread that happens to work most of the time.

What you get back

Solutions use optionals as the type system intends — `if let`, `guard let`, and optional chaining rather than force unwrapping. Structs are the default and classes appear when identity matters, with the answer saying which it is relying on. Closures that capture self show the capture list, because the interviewer is watching for exactly that line.

Example prompts

Questions people are actually asked

Send the transcript straight to the coding surface, or snip the problem off the screen.

  • Where is the retain cycle in this view controller, and how do you break it?

  • When would you choose a struct over a class here?

  • Convert this completion-handler API to async/await.

Where candidates lose points

Swift-specific traps

Force unwrapping

An exclamation mark in interview code is a crash you have chosen to accept, and it is the first thing an iOS interviewer's eye goes to.

Missing capture lists

A closure that captures self strongly inside a class creates the retain cycle the round was built around.

Assuming reference semantics

Mutating a struct passed into a function changes a copy. Candidates who expect otherwise reveal they have been writing Swift as if it were Objective-C.

Three surfaces

One workspace, three kinds of round

Chat

Behavioral rounds and the “tell me about a time” half of a technical screen, in your own voice.

Live coding

A structured solution with the reasoning attached, so you can talk through the code while you write it.

System design

Architecture answers with the diagram rendered inline, not described in prose.

Choosing a model

GPT-5.4 Mini is adequate for the coding half of an iOS screen. Give the ARC and concurrency questions to GPT-5.4 — retain-cycle reasoning depends on precisely which reference is strong, and that is where a fast model guesses.

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