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Live coding round

Senior iOS live coding interview

At senior level the coding task may look similar, but the bar is judgment. Interviewers are watching for the signals that separate someone who can code from someone who can own ambiguous problems.

What senior signals look like

Senior candidates clarify scope before coding, choose the simplest design that fits, and name trade-offs instead of chasing perfection. They handle edge cases deliberately, keep the code readable for a reviewer, and know when a solution is good enough to stop. They also recover from mistakes visibly and calmly.

How to demonstrate seniority live

Frame the problem as you would for a teammate, state assumptions, and explain why you chose one approach over another. Talk about testing and failure modes unprompted. When you hit a wall, narrate the recovery. That combination of restraint, communication, and ownership is what reads as senior rather than merely competent.

The same task, graded on a different curve

Companies often reuse a mid level task for senior loops and change only the rubric. The task might be a paginated list with caching. A mid level pass is a working list. A senior pass is a working list plus unprompted answers to the questions nobody asked: what happens on a refresh mid scroll, who owns the cache when memory pressure hits, how does this behave offline. When I calibrate interviewers, the instruction is simple: for senior, score what they raise on their own. Anything you had to prompt for does not count toward seniority, even if the answer was excellent. That is the whole game. The prompts you preempt are the score.

Trade-off lines that read as senior

Seniority shows up in sentences with a because and a cost in them. Each of these takes 15 to 30 seconds out loud. On concurrency: I will start with async await and no actor, because there is no shared mutable state yet, and adding isolation early costs readability for no safety. On caching: I am keying the cache by URL and capping it at a count, not bytes, because a byte budget is better but not in the first 20 minutes. On architecture: I will keep this in one file for the interview and say where the seams are, because premature extraction here would just be theater. Notice each line names the road not taken. Interviewers cannot score a trade-off you never mention, and mid level candidates mention almost none.

The over-engineering trap

The most common senior failure I see is not weak code, it is too much of it. The candidate hears senior and builds a protocol, a generic cache layer, and a dependency injected client for a 40 minute task. The follow-up that springs the trap is quiet: why does this need a protocol. If the honest answer is testability you have not used yet, the abstraction just became evidence against you. The strong position is the opposite: build the concrete version, and narrate where you would cut the seam when a second implementation actually appears. The recovery line if you are already three protocols deep: I have over abstracted this for the time we have, let me collapse it to the concrete version and keep the one seam the test needs.

Questions a senior candidate asks the interviewer

At senior level the clarifying phase is itself scored, and generic questions waste it. Strong openers I have heard in real rounds: is the payload contract stable or should I decode defensively, is this component ever touched from more than one task at once, and do you care more about the data layer or the UI layer for this exercise. Each question changes the design, which is what marks it as senior. Asking what the input looks like is fine. Asking which failure mode the interviewer cares about tells them you have shipped things that failed, and that you know interviews are built around failure modes on purpose.

What the debrief actually weighs

In senior debriefs the coding signal is usually settled in the first sentence and the rest of the discussion is judgment. Did they scope before building. Did they change course cleanly when challenged. Did they know when to stop. Hiring committees fight over borderline mid level candidates. For senior loops the pattern is starker: one strong judgment signal, like a well argued decision to not build something, routinely outweighs a missed edge case. Prepare accordingly. Rehearse the narration and the trade-off lines with the same seriousness you rehearse the Swift, because the debrief conversation is mostly about the former.