📱 Mobile Dev

Structuring an auth flow in React Navigation

Conditionally render an auth stack versus app stack from state, not navigate calls; store token; let state drive screens.

Stack Navigator vs Tab Navigator and nesting

A Stack pushes and pops screens for hierarchical drill-down; a Tab switches between parallel top-level sections. Nesting a Stack in each tab gives each tab its own independent push/pop history.

navigate vs push in a Stack Navigator

Navigate goes to an existing instance of the route if present, otherwise pushes; push always adds a new instance onto the stack. Use push to revisit the same screen with new params.

advanced2 min read

Gesture Handler and Reanimated on the UI thread

Gesture Handler tracks gestures natively and Reanimated runs worklets on the UI thread, so animations driven by shared values continue smoothly even when the JS thread is blocked.

keyboardShouldPersistTaps in ScrollView

KeyboardShouldPersistTaps controls whether taps dismiss the keyboard or reach children; values never, always, and handled.

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.

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.

Button vs TouchableOpacity vs Pressable

Button is minimal and platform-styled with limited customization; TouchableOpacity wraps children with an opacity fade; Pressable is the modern, flexible primitive exposing rich press states.

Controlled TextInput with value and onChangeText

Store input text in state, bind value to that state, and update state in onChangeText so React is the single source of truth.

How StyleSheet.create reduces styling overhead

StyleSheet styles are created once with stable references, so identical renders skip reallocation and reduce diffing and serialization work; inline literals allocate new objects each render…

Why Text inherits styles but View does not

Nested Text inherits text styles because it maps to platform attributed-text rendering, while Views are independent layout boxes with no style cascade.

Circular View with centered text

Set equal width and height, borderRadius to half that, then justifyContent and alignItems center to place the Text in the middle.

Using position absolute in React Native

Absolute removes a view from flex flow and positions it relative to its nearest positioned ancestor using top, left, right, bottom; ideal for overlays and badges.

alignItems vs justifyContent in flexbox

JustifyContent aligns along the main axis, alignItems aligns along the cross axis; with column direction main is vertical and cross is horizontal.

Default flexDirection and header-content-footer layout

Default flexDirection is column, unlike web's row; give the root flex 1, fixed heights to header and footer, and flex 1 to a scrollable middle.

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.

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.

Building a native module from scratch

Write a native module class with exported methods or constants, register it via a package, then expose a typed JS wrapper.

Improving React Native startup time

Enable Hermes for fast bytecode startup, shrink and lazy-load the JS bundle via inline requires and RAM bundles, and defer non-critical native init.