Interview questions in Mobile Dev, page 5
What is a Dart factory constructor and common use cases?
Explain a factory need not create new instances and can return cached objects or subtypes; contrast with generative ones; give JSON or singleton examples.
Hot vs cold Kotlin Flows and StateFlow use case
Tests grasp of flow lifecycle and collector behavior. A strong answer contrasts cold Flows, which restart per collector, with hot StateFlows broadcasting to all observers. Red flag: using Flow for UI state without citing config changes or initial value.
Hot vs. Cold Streams: `StateFlow` vs. `Flow`
Tests your grasp of stream lifecycles. A great answer defines cold Flow (lazy, per-collector) vs. hot StateFlow (shared, active), then uses a ViewModel UI state scenario to show why StateFlow is correct for surviving configuration changes.
Hot vs. Cold Streams: StateFlow vs. Flow in Android
This tests your grasp of stream lifecycles. A great answer defines cold Flow (lazy, per-collector) vs. hot StateFlow (active, shared state) and uses a ViewModel UI state scenario. A red flag is mischaracterizing a Flow as a one-time operation.
Single useState object for multi-input forms
Hold all fields in one state object, use a generic handler keyed by field name, and update immutably by spreading previous state.
What LLDB command prints a UIView description versus an Int?
Tests LLDB formatting at breakpoints. Great answers: po invokes description or debugDescription on objects, while p evaluates and prints raw primitive values with type info. Red flag: mixing them up or recommending console print instead of LLDB.
How do you model Product and safely parse JSON into List<Product>?
Tests bridging dynamic JSON to Dart's type system. A strong answer uses an immutable Product with a factory constructor that validates fields and converts types, mapping over the list. Red flag: leaving everything dynamic or assuming perfect API data.
What is a CoroutineDispatcher and when to use Default versus IO?
This tests thread pool selection and the CPU versus IO distinction. A strong answer maps CoroutineDispatcher to the thread pool, Default to CPU work, IO to blocking IO, and Main to the UI thread.
What is a CoroutineDispatcher and when do you use each type?
Tests your grasp of coroutine threading. A dispatcher manages which threads a coroutine runs on. Explain Main for UI, Default for CPU-intensive work, and IO for blocking operations. A red flag is mixing up IO and Default or using Unconfined.
What is a CoroutineDispatcher and when to use IO vs Default?
Tests your grasp of thread pool strategy for CPU vs. I/O-bound tasks. A good answer defines Dispatchers, contrasts the fixed-size Default pool (for CPU work) with the larger IO pool (for blocking I/O), and gives clear examples.
Gesture Responder System lifecycle
A single view becomes the responder for a touch; onStartShouldSetResponder claims it at touch start, onMoveShouldSetResponder claims it on movement, then grant, move, and release callbacks fire.
What is an Xcode Scheme? How do you configure a custom one?
This tests Xcode build orchestration. A scheme is a blueprint for build, test, run, profile, analyze actions; a strong answer covers duplicating it, setting launch arguments, and staging configs. A red flag is confusing schemes with build configurations.
How does Dart resolve mixin method conflicts and application order?
Tests understanding of Dart's mixin linearization. Answer: Dart applies mixins left-to-right, building a superclass chain where the last mixin wins conflicts. Red flag: claiming first mixin wins or confusing with multiple inheritance.
Explain Kotlin's declaration-site variance with in and out
Out T means covariant producer (read), in T means contravariant consumer (write), removing wildcard noise.
Explain Kotlin's declaration-site variance with `in` and `out`
This tests your grasp of type systems and API design. Explain how out (covariance/producer) and in (contravariance/consumer) provide type safety at the declaration site, simplifying usage. A red flag is confusing variance with immutability.
Explain Kotlin's declaration-site variance with in and out
This tests your grasp of generic type safety and API design. Explain that out marks covariant producers (e.g., List<out E>) and in marks contravariant consumers, then contrast this cleaner declaration-site model with Java's repetitive use-site wildcards.
keyboardShouldPersistTaps in ScrollView
KeyboardShouldPersistTaps controls whether taps dismiss the keyboard or reach children; values never, always, and handled.
Explain symbolic breakpoints and debug Auto Layout with one
Tests debugging closed-source frameworks without source lines. A strong answer says a symbolic breakpoint stops on UIViewAlertForUnsatisfiableConstraints, then checks the backtrace or log to find the bad view.
Define a Dart Future, return Future<String>, and handle errors with both patterns.
Tests Dart async primitives and error handling. A strong answer defines Future as a pending async result, writes a delayed Future<String>, consumes it with then/catchError, and mirrors with async/await try/catch.
How do buffer, conflate, and collectLatest manage Kotlin Flow backpressure?
Backpressure is fast emit vs slow collect; buffer() suspends the producer when full, conflate() drops stale values, and collectLatest() cancels active collection to…
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