Senior mobile interview preparation
Prepare for the mobile interview you actually have.
A correct answer is the entry fee. The round is scored on what happens after it: the follow-up, the constraint that changes, the trade-off you have to defend out loud.
- Question
- Design the image loading for a feed of 10,000 posts.
- First answer
- An in-memory cache in front of URLSession, keyed by URL, with a disk cache behind it.
- Then
- “The feed scrolls fast on a three-year-old phone and memory warnings start. What do you change first?”
- What is scored
- Whether you size the cache by cost not count, cancel off-screen work, decode off the main thread, and say which of those you would measure before touching.
Start from your platform
Four platforms, described as they are.
iOS and Android have books and interactive practice. Flutter and React Native have question banks today; the page for each says exactly what exists.
Books and interactive practice
iOS interview prep
Swift concurrency, SwiftUI state, architecture, and the system design round senior loops add.
See the iOS route →Books and interactive practice
Android interview prep
Coroutines, Compose, lifecycle, architecture boundaries, and the Android design round.
See the Android route →Question bank
Flutter interview prep
State management, rendering, platform channels, and the machine coding round.
See the Flutter route →Question bank
React Native interview prep
The JS and native boundary, performance, the new architecture, and state.
See the React Native route →What the interviewer writes down
Four things get scored, and none of them is “knew the answer”.
Every guide and every book here is organised around the same four signals, because they are what separates a senior answer from a correct one.
- 01
Signal
Does the first answer say something only an engineer who has shipped this would say?
- 02
Structure
Can the interviewer follow the reasoning, or do they have to reconstruct it from fragments?
- 03
Depth
What happens at the second and third question, when the textbook answer runs out?
- 04
Judgment
When the constraint changes, does the answer change, and can you say why?
Choose by the time you have
The right material depends on the round and the calendar.
Interview this week
Triage, not a curriculum. Cover the questions that come up and the depth they are scored at.
The 24-Hour books →Weeks to prepare
The full loop for your platform: fundamentals, architecture, design and the senior follow-ups.
The platform blueprints →A live coding round
Coding while someone watches: narrating decisions, recovering when you stall, defending a choice.
Share Your Screen →A system design round
Mobile constraints the backend version skips: offline, sync, battery, memory, release trains.
Mobile System Design Blueprint →Not sure which? Answer four questions and get one recommendation with the reason for it.
Interview guides