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Mock interviews by role · Software & Engineering

Mobile Developer mock interview

Mobile interviews focus on constraints a web candidate can ignore: flaky networks, store review, battery, and users who do not update. Interviewers want those constraints in the answer, not a tour of the framework.

Pick the platform you actually ship and use its vocabulary. A honest iOS answer beats a generic answer that tries to cover both platforms badly.

Practice this role with an AI interviewer

What the loop usually looks like

  1. Screen

    30 min

    An app you shipped, the platform, and a store or crash issue.

  2. Practical or design

    45–60 min

    A screen with offline or a slow network, or a debugging exercise from a crash log.

  3. Collaboration

    30 min

    Working with API and design when the client cannot be updated instantly.

What interviewers score

  • Offline and slow networks
  • Release safety
  • Performance and battery
  • API compatibility

10 mobile developer interview questions and model answers

  1. Technical

    1. How should a screen behave when the network drops mid-save?

    What they are testing: Offline UX.

    I keep the draft on device and show that it is not on the server yet. When the network returns I retry the same request with an idempotency key. I do not show a success checkmark until the server accepts the write.

  2. Technical

    2. Users on an old version will exist for months. How do you change the API?

    What they are testing: Client compatibility.

    I add fields and keep the old contract working. The new app uses the new fields. I do not require an update for a bug fix unless the old client is unsafe, and then I use a forced-upgrade path I have already tested.

  3. Domain

    3. What do you check before a store release?

    What they are testing: Release discipline.

    Crash-free sessions on the release candidate, the login and purchase paths on a physical device, and the rollback plan, which on mobile often means a server flag because the store binary cannot be unsent quickly. Release notes match the binary.

  4. Technical

    4. A screen janks when a list grows. What do you look at?

    What they are testing: Rendering performance.

    I profile on a low-end device. I look for work on the main thread: image decode, large layouts, or binding too much data. I page the list and size images to the slot. I do not trust the simulator alone.

  5. Situational

    5. Design wants a gesture that conflicts with the system gesture. What do you do?

    What they are testing: Platform fit.

    I show it on a device with the system gesture enabled. If users will trigger the system action by accident, I ask for a different affordance. Platform conventions are part of the requirement.

  6. Behavioral

    6. Tell me about a crash you diagnosed from a report, not from your own phone.

    What they are testing: Production debugging.

    The report showed a null user after a logout race. I reproduced it by backgrounding the app during logout. The fix cancelled the in-flight request and ignored its result. I added a test that logs out while a request is open.

  7. Technical

    7. Where do you store a session token?

    What they are testing: Security on device.

    In the platform keystore or keychain, not in plain preferences and not in a log. The app handles a missing token by returning to login. I do not invent a second copy in memory that outlives logout.

  8. Behavioral

    8. Describe a time you cut a feature because of a platform limit.

    What they are testing: Judgment.

    We wanted background upload of large video. The operating system suspends that work. We shipped user-initiated upload on Wi-Fi with progress, and we wrote the limit in the spec so it did not come back as a bug.

  9. Domain

    9. How do you test on devices you do not own?

    What they are testing: Coverage.

    I keep a small matrix: one current phone, one old OS version, and one small screen. The rest is a device lab or a teammate’s hardware for the release candidate. I note what I did not run.

  10. Situational

    10. Analytics show a button almost nobody taps. What do you ask before removing it?

    What they are testing: Product partnership.

    I ask whether the few taps are a critical task for a small group, like account deletion. Volume alone is not importance. If it is truly unused and not a legal or safety path, I support removing it.

Frequently asked questions

Should I prepare both iOS and Android?

Prepare the one you ship. If the role is cross-platform, be ready to name one difference in navigation, storage, or release, not to pretend the platforms are the same.

Do mobile loops include algorithms?

Some do. Product-heavy loops replace one with a UI or debugging exercise. Look at the posting and practice the exercise type it implies.

How do I talk about the app store delay?

Say which bugs you fix with a server flag and which ones need a binary. That distinction is the seniority signal.

Can I practice without a laptop demo?

Yes. Talk through the screen states in a voice mock. Bring one crash or release story with the platform named.

Keep practicing