Question 1
Which part of this product has to work on a flaky network, and what do you show while it does not?
Approach. Name the offline or retry behavior and the state the user can still trust.
Mobile engineer interview questions from a job description
Turn a mobile engineer job description into likely iOS, Android, or cross-platform questions, with a prep checklist.
Matched in your browser from the requirements in the posting and Luna’s interview-question hub. These are practice prompts, not a claim that this wording will be asked.
Requirements in the posting
Mobile Engineer
Build the iOS and Android app, with room for shared client code.
You will:
- Ship features in Swift and Kotlin, and use React Native where it earns its place
- Design for a flaky network: retry, offline state, and what the user can still trust
- Treat App Store and Play release constraints as part of the design
- Debug crashes that only show up on a subset of devices
- Collaborate with backend engineers on the API the app can retry
We will ask you to narrate one screen’s data flow without opening a project.
Build the iOS and Android app, with room for shared client code.
You will:
- Ship features in Swift and Kotlin, and use React Native where it earns its place
- Design for a flaky network: retry, offline state, and what the user can still trust
- Treat App Store and Play release constraints as part of the design
- Debug crashes that only show up on a subset of devices
- Collaborate with backend engineers on the API the app can retry
We will ask you to narrate one screen’s data flow without opening a project.
Likely questions
Coding
Mobile
Ship features in Swift and Kotlin, and use React Native where it earns its place
Question 2
How would you ship a mobile change without waiting on a store review for every fix?
Approach. Separate what can be configured from what needs a binary, and say the risk of each.
Coding
Android
Build the iOS and Android app, with room for shared client code.
Question 3
How do you keep an Android screen correct across rotation, backgrounding, and a slow response?
Approach. Say what state survives and what you refetch, in terms of the flow in the posting.
Question 4
Which device or OS split matters for this app, and which would you stop trying to cover?
Approach. Name the split that hits users and the long tail you would sample instead of boil the ocean.
Coding
iOS
Ship features in Swift and Kotlin, and use React Native where it earns its place
Question 5
How would you structure an iOS screen for the main task in this posting?
Approach. Name where state lives and what you would keep off the main thread.
Question 6
What is different about testing an iOS change versus a web change for this team?
Approach. Mention the device or OS split you would actually cover, and the one you would sample.
System design
Backend services
Collaborate with backend engineers on the API the app can retry
Question 7
Where would you draw the service boundary for this product, and what would you keep in one process for now?
Approach. Start from the request that must be fast, then name the split you would postpone.
Coding
React
Ship features in Swift and Kotlin, and use React Native where it earns its place
Question 8
Sketch a React component this posting would need. What state is local, and what is passed in?
Approach. Start from the user action, name the state, and say what you would not put in state.
System design
APIs
Collaborate with backend engineers on the API the app can retry
Question 9
Design the API a client of this product would call first. What is the request, the success, and the error?
Approach. One resource, the idempotency story, and what the user sees on a timeout.
Behavioral
Collaboration
Collaborate with backend engineers on the API the app can retry
Question 10
Tell me about a disagreement with someone who did not report to you. What did you do with their objection?
Approach. Name the objection, what you changed, and what you did not. Do not flatten it into “we aligned.”
What to prepare
- Practice one mobile constraint out loud: offline, a slow network, or a small screen.
- Be ready to talk about one lifecycle bug and the state you had to keep.
- Explain one screen’s data flow in Swift without opening a project.
- Draw one service boundary and say what you would not split out yet.
- Rebuild one component from a blank file and narrate where state lives.
- Write one endpoint on paper: method, body, error, and what a retry should do.
- Have one story where someone disagreed and you kept the working relationship.
Mobile postings tell you the platform in the first bullets. Swift is an iOS loop. Kotlin is Android. React Native or Flutter is a cross-platform loop that still asks about the network, the store, and the device split. “Offline” and “flaky network” are more predictive than the word mobile itself.
Release bullets become “what can you fix without a store review?” Crash bullets become a subset-of-devices story. If both platforms are listed as equal, they may still go deep on one. Prepare the one you have actually shipped.
The sample names both a native constraint and a shared client. Highlighted lines are the likely question sources.
Sample job description
The posting below is already in the tool. The questions are the ones its requirements point to. Replace it with a posting you are actually interviewing for.
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