Easy interview questions in Mobile Dev
Expo managed workflow vs bare React Native
Expo gives fast setup, OTA updates, managed builds, and prebuilt APIs; bare gives full native control and arbitrary native modules.
What is the difference between let and var in Swift?
This tests value semantics beyond syntax. A strong answer defines let as immutable and var as mutable, notes that let on a reference type only fixes the pointer, and cites clearer intent and compiler optimization.
What is the difference between final and const in Dart?
Tests compile-time versus runtime immutability in Dart. A strong answer: final allows single assignment at runtime, but const requires a compile-time constant and deep immutability.
Explain val vs var in Kotlin and null safety risks
Val is read-only, var is mutable; nullables use ? like String?; risk is NullPointerException if checks are missed.
Explain val vs. var and null safety in Kotlin
Tests your grasp of Kotlin's core principles: immutability and compile-time null safety. Define val (read-only) vs. var (mutable), declare nullables with ?, and identify the risk as runtime NullPointerExceptions.
Explain val, var, and null safety in Kotlin
This tests your grasp of immutability and Kotlin's compile-time null safety. Define val (immutable reference) vs. var (mutable), explain nullable types using ?, and state the risk is NullPointerException. A red flag is confusing val with a constant.
What do the safe call and Elvis operators do in Kotlin?
?. yields null if receiver is null; ?: provides the right operand when left is null; chain as val len = str?.length ?: 0.
What is an optional in Swift? Demonstrate two safe unwrapping methods.
This checks Swift type safety and nil-handling. A strong answer defines Optional as an enum, demonstrates if let binding, and shows the nil-coalescing operator ?? for defaults. Avoid suggesting force-unwrapping with ! as a safe pattern.
Explain Dart positional vs named parameters and write one signature
Tests Dart parameter syntax. A strong answer covers required positional args, optional positional args in square brackets, and named args in curly braces with defaults. Red flag: claiming named parameters are always optional or confusing bracket types.
Purpose of Kotlin's safe call (`?.`) and Elvis (`?:`) operators?
This tests your grasp of Kotlin's null safety philosophy. A good answer defines the safe call (?.) for conditional access and the Elvis operator (?:) for default values, then combines them. A red flag is using verbose if/else checks for simple cases.
Purpose of safe call (`?.`) and Elvis (`?:`) operators
This tests your grasp of Kotlin's idiomatic null safety. Explain the safe call (?.) for chaining on nullables and the Elvis operator (?:) for providing defaults. Combine them in a one-line example. A multi-line if/else is a red flag.
How does Swift's switch differ from C's switch?
Switches must be exhaustive, there is no implicit fallthrough between cases, and cases can match ranges, tuples, and bind values.
Inline styles vs StyleSheet.create
Styles are JS objects passed to the style prop; StyleSheet.create registers styles once for stable references and validation, while inline objects recreate on each render.
View vs Text and nesting rules
View is a flexbox layout container; Text renders and lays out text with inheritance. Text nests inside Text and inherits style; View inside Text is constrained and discouraged.
Swift struct vs class: differences and when to choose each
Tests value vs reference semantics and let mutability. Strong answers contrast copy behavior with shared references, note allocation tendencies, and choose struct for value semantics or class for identity.
Explain protocols and how extensions provide default implementations
Tests behavior sharing without inheritance. A strong answer defines protocols as requirements, shows extensions injecting default implementations, and contrasts this with base-class inheritance.
Convert List<User> to Map<String, User> keyed by user id
Tests Dart collection-to-map idioms. A strong answer picks the for-element literal {for (var u in users) u.id: u}, mentions Map.fromIterable as a verbose alternative, and flags duplicate-key overwrites. Red flag: manually looping to populate an empty map.
Explain the difference between launch and async in Kotlin Coroutines
This tests scope behavior and side effects versus results. A strong answer says launch returns a Job for side effects, async returns a Deferred for results, and both are scope children. A red flag is using async for all tasks or ignoring exception handling.
Difference between launch and async in Kotlin Coroutines
This tests your grasp of coroutine result handling and exception propagation. Explain that launch is fire-and-forget (returns Job), while async is for results (returns Deferred). Mention async defers exceptions until await().
Explain launch vs. async in Kotlin Coroutines
Tests your grasp of structured concurrency, return values, and exceptions. launch is for fire-and-forget tasks (returns Job), while async is for tasks that produce a result (returns Deferred).
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