Advanced Flutter Interview Questions
6 questions
How does Flutter manage memory, and how do you avoid leaks?
Dart uses automatic garbage collection, so you don't free memory manually — leaks in Flutter almost always come from long-lived objects (controllers, streams, listeners) holding references that prevent disposed widgets' resources from being collected.
What is Firebase Remote Config used for?
Remote Config lets you change app behavior and appearance — feature flags, A/B test variants, default values — without shipping a new app release, by fetching key/value parameters from the Firebase backend at runtime.
What is Dependency Injection and how is it used in Flutter?
Dependency Injection means a class receives its dependencies from the outside (via constructor or a container) instead of creating them itself, which decouples classes from concrete implementations and makes them easy to test with substitutes.
What are isolates in Dart and when do you need them?
An isolate is Dart's unit of concurrency — a separate memory heap and event loop running independently, with no shared mutable state — used to run CPU-heavy work in parallel without blocking the UI thread.
What is CustomPainter used for?
CustomPainter lets you draw directly onto a canvas with low-level drawing primitives (paths, arcs, text, gradients) for visuals that no combination of standard widgets can produce — charts, custom shapes, signature pads.
What are platform channels and why are they needed?
Platform channels are Flutter's message-passing bridge to native platform code (Kotlin/Java on Android, Swift/Objective-C on iOS) — used whenever you need a platform API or native SDK that has no Dart equivalent.