Interview round · every platform

Senior and Staff mobile interview prep

At Senior and Staff the questions often look the same as at mid level. What changes is the second question, how far the answer has to reach, and whether you can show the decision was yours.

For: Engineers interviewing for a Senior, Staff, Lead or Architect mobile role.

Mike Salari · Staff mobile engineer · 500+ technical interviews from the hiring side

Read the 7 guides Build my prep plan

What the round scores

Part of the round	What the interviewer writes down
Depth under follow-up	Whether the answer holds at the second and third question, when the textbook runs out.
Scope	Senior: the feature and the team. Staff: several teams, the migration, the org around the system.
Judgement	When the constraint changes, the answer changes, and you can say why.
Evidence	Concrete decisions you made, with the outcome, not what the team did in general.

Loops differ by company. This is the common shape of the round in senior mobile loops, not a promise about any one employer.

A weak answer and a strong one

Weak

"We used coroutines and it worked well."

Strong

"I moved the sync to a scope owned by the repository because the screen scope cancelled uploads on rotation; failed uploads dropped to near zero."

Weak

Staff answer that is a longer Senior answer.

Strong

Staff answer that names who else is affected, the migration path, and how it will be reversed if it fails.

For senior mobile engineers moving toward Staff, architect or tech lead scope, where a design or architecture round is judged on how far the answer reaches beyond the app. It connects the client to backend, security, reliability and the organisation around the system. It is not a fundamentals book and not LeetCode practice.

The second question

Follow-ups that decide the round

“What would you do differently if you designed it again?”

Tests reflection and ownership, a Senior and Staff signal in almost every loop.

“Who else had to agree to this change, and how did you get there?”

Tests Staff scope: influence across teams, not only technical correctness.

“How would you know, a month after release, that this was the wrong call?”

Tests whether you design with measurement and reversibility in mind.

How to prepare for it

Read the senior questions for your platform
Each guide shows the first answer and the follow-up that separates levels.
Prepare three decision stories
Decision, alternatives, cost, outcome. Short enough to say in two minutes.
If you are aiming at Staff
Practise the design round at Staff scope: migration, rollout, other teams, reversal.

Guides for this round

iOS · 16 min

Senior iOS interview questions for 2026, and the follow-ups

Twelve senior iOS interview questions for 2026: what each scores, a weak and a senior answer, and the follow-up on Swift 6 concurrency, SwiftUI, architecture.

Android · 16 min

Senior Android interview questions and what follow-ups test

Twelve senior Android interview questions with what each scores, a weak and a senior answer, and the follow-up: coroutines, Flow, Compose, process death.

Flutter · 15 min

Senior Flutter interview questions and follow-ups

Twelve senior Flutter interview questions on rendering, keys, state, isolates, platform channels and architecture, with the follow-up to each.

React Native · 13 min

Senior React Native interview questions and follow-ups

Ten senior React Native interview questions on migration, startup, retries, old app versions, feature flags and native rewrites, with the follow-up to each.

Senior and Staff loops · 15 min

Staff mobile system design interview, scored against Senior

How I decide Staff vs Senior in a mobile system design loop: the questions I ask, what each level answers, the follow-ups, and how down-levelling happens.

iOS · 15 min

Senior iOS mock interview: a full loop for 2026

A senior iOS mock interview loop: four 45 to 60 minute rounds, escalating follow-ups, senior versus mid-level answers, a rubric and a debrief template.

Senior and Staff loops · 13 min

FAANG mobile mock interview: a full loop to practise in 2026

A FAANG mobile mock interview you can run with a partner: what Google, Meta, Amazon and Apple publish about their loops, seven practice prompts and a rubric.

Books and practice

For senior, staff and principal engineers, tech leads and architects who are accountable for results they cannot order into existence. It teaches finding the decision behind a request, moving it before the review, and keeping it decided. It is not a list of leadership principles.

For staff and principal mobile engineers, mobile architects and platform leads who decide which boundary is worth its cost and how a live system keeps changing. It treats MVVM, TCA, VIPER, RIBs and feature modules as responses to pressure, not destinations, and covers state ownership, offline sync, version skew, release control and AI on mobile. It assumes you can already build and ship a mobile app; it is not a first architecture book.

For a full senior Android interview loop with time to prepare it properly. It is written for mid level to Staff and architect candidates and reasons about current Android practice rather than definitions, from the language and concurrency questions to the Android system design round. When the interview is days away, the 24-Hour Android book is the faster start.

For iOS and Android, Interview Runtime is the practice layer: interview answer practice where you speak first and the follow-up comes after, the way a real round runs. It is for engineers who have read enough and now need to hear where their own answer breaks. The free iOS sample shows how it works before you buy.

Other rounds

Mobile system design

Prepare for the mobile system design round: offline behaviour, sync, caching, lifecycle and release, and what the interviewer scores at Senior and Staff.

Coding and live coding

Prepare for mobile coding, live coding and pair programming rounds: the tasks that recur, how they are graded, and what to say while you type.

Architecture

Prepare for the mobile architecture round on iOS, Android and Flutter: module boundaries, dependency direction, state ownership and defending your pattern.

Swift, SwiftUI and UIKit

Prepare for the Swift, SwiftUI and UIKit rounds of an iOS interview: concurrency and isolation, memory, state and identity, and what each question scores.

Kotlin and Jetpack Compose

Prepare for the Kotlin, coroutines and Jetpack Compose rounds of an Android interview: structured concurrency, Flow, recomposition and state.