Junior
App lifecycle: states, screens and the basics that change everything
Foreground, background, terminated: the states of an app and why ignoring the lifecycle causes the most common mobile bugs.
Jun 24, 2026
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Mobile
What a mobile developer needs to master at each stage of their career. From the lifecycle of a screen to testable architecture and publishing to the stores — the concepts that come up in technical interviews and in day-to-day work, explained plainly. Filter by level below.
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Junior
Navigation in apps: stack, tabs and deep links
How the user moves through the app: screen stack, tabs, the back button and deep links that open the right screen from a link.
Jun 22, 2026
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Junior
Layouts that adapt: density, safe areas and different screens
Pixels are not pixels. Screen density (dp/pt), safe areas (notch), and how to build a UI that works from small phones to tablets.
Jun 20, 2026
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Mid-level
State and data on mobile: from local to global management
Screen state vs app state, local cache, on-device database and when to reach for a global state solution.
Jun 17, 2026
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Mid-level
Offline-first and sync: the app that works without a network
Connectivity is unreliable. How to store data locally, queue changes and sync later — resolving conflicts without losing data.
Jun 15, 2026
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Mid-level
Mobile performance: jank, lists and battery usage
60fps or the user feels it. What causes jank, how long lists should be built, and why network and battery are a budget, not infinite.
Jun 13, 2026
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Senior
Mobile architecture: MVVM, layers and testability
Separating UI, logic and data for an app that grows without turning into chaos. MVVM/MVI, layers and why this makes code testable.
Jun 10, 2026
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Senior
Push notifications: how they work end to end
From your server to the user's device: tokens, APNs/FCM, payload and why push delivery is never 100% guaranteed.
Jun 8, 2026
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Senior
Publishing to the stores: build, signing, review and versioning
The road to the store: release build, code signing, the review process and how to version so you don't break existing installs.
Jun 6, 2026
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Self-assessment: where are you?
Check what you already master. Your progress is saved in this browser only.
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Quiz: test what you learned
Four questions per level, with an explanation and the article that covers each topic. Ace a level and you can mark it in the self-assessment above.