Project Setup

pod install reads ios/Podfile, resolves React Native's pods and every native library's pods, writes Podfile.lock and generates a Pods project plus an .xcworkspace that joins it to the app project, so Xcode must build the workspace.

React Native's JavaScript runs on the device with no Node process, so process.env holds only NODE_ENV. Per-environment values must be inlined into the bundle at build time or read from native build config, and both are readable in the shipped app.

Metro compiles .ts and .tsx with Babel, where @react-native/babel-preset's TypeScript plugin deletes type annotations without checking them. Type errors are only reported by tsc, which @react-native/typescript-config runs as a noEmit checker.

Bump react-native and react to the versions the Upgrade Helper's package.json shows, then hand-apply its diff of the project template to the iOS, Android and JavaScript config files, update native libraries, reinstall pods and rebuild both platforms.

DEV is true only when the JavaScript bundle was built in development mode and false in any release bundle. It says nothing about the backend: a staging build installed by testers is a release build, so it sees false exactly like production.

Run npx @react-native-community/cli@latest init MyApp, optionally with --version to pin a React Native release or --template for a custom template. The old react-native init was deprecated in 0.75 and stopped working in 0.77.

The scripts call the React Native CLI's run-ios or run-android, which builds the native app with Xcode or the Gradle wrapper, installs it on a simulator, emulator or device, and launches it; a debug build then loads its JavaScript from Metro.

The base config encodes React Native's type-checking setup: strict checks, noEmit, JSX kept as react-native, bundler-style resolution with the react-native export condition Metro uses, Jest types and skipLibCheck. It is versioned with React Native, so upgrades update it.

React Native ships a new minor, which may contain breaking changes, roughly every two months and maintains only the latest three minor series. When 0.87 shipped, 0.84 became unsupported: it gets no further patches, even for bugs that affect you.

Give each environment its own native variant and app identity: Android product flavors with applicationIdSuffix, iOS build configurations with their own bundle identifier selected by a scheme. Each variant then feeds its own config file, which carries the API URL into the build.

The native iOS and Android projects are generated once at init and then become source code you commit, edit and maintain yourself, including applying the template's native changes by hand at every React Native upgrade.

The JDK runs Gradle and compiles Java and Kotlin (React Native targets Java 17); the Android SDK supplies the platform named by compileSdk (37 in 0.87) plus build tools; the Gradle wrapper pins the Gradle version the project was tested with.

Xcode's build phases run in a non-interactive shell that never loads a version manager like nvm, so node may not be on PATH. React Native's phases read NODE_BINARY from ios/.xcode.env, then from the uncommitted, machine-specific ios/.xcode.env.local.

tsconfig paths only teach tsc where to find types; nothing rewrites the import for Metro. Add the same alias to babel.config.js with babel-plugin-module-resolver, then restart Metro with --reset-cache, since its transform cache does not track babel.config.js.

List every dependency that ships native code, check each one's README, changelog and React Native Directory entry for support of the target version, note required upgrades or blockers, then prove it with a clean iOS and Android build on a branch.

On Android, the React Native Gradle Plugin bundles every variant not named in debuggableVariants, whose default lists only debug and debugOptimized. On iOS, the bundling build phase treats configurations whose name contains Debug as development builds. Flavored variants break both assumptions.

Add React Native to the native apps, register a root component with AppRegistry, and host it natively: RCTReactNativeFactory on iOS, a ReactHost with a ReactActivity or ReactFragment on Android. Watch names, release bundling and minimum OS versions.

Walk the chain pod install depends on: JavaScript packages installed, Node inside React Native's engine range, the Gemfile's CocoaPods run through Bundler, and a full Xcode of at least 16.1 selected. The first failing link's error message names it.

React Native 0.87 made the Strict TypeScript API the default: source-generated types scoped to the root react-native export. Deep imports lose their types and refs need *Instance types; migrate, or opt out temporarily through 0.88.

Stepping 0.84 to 0.85 to 0.86 to 0.87 keeps each diff small, lets you see each deprecation warning before the removal it announces, and ties any regression to one release; a single jump mixes three sets of breaking changes into one failing build.

Usually yes: native engineers can still write custom modules and configuration inside a framework, which absorbs routing, builds and upgrades. Go bare only for concrete constraints, such as embedding in native apps or needing core releases early.

Upgrade every minor, or at least every other one, soon after its first patch release, so the app never leaves the three-series support window; give upgrades an owner and a sprint budget, gate them on library support, and verify each on both platforms.