Deep Linking

Deep linking maps a URL to a screen inside your app. Tapping myapp://post/42 in an email, a push notification or another app launches yours and lands the user on post 42 rather than the home screen.

The simplest form is a custom URL scheme such as myapp://. You register it natively (CFBundleURLTypes in Info.plist, an intent-filter in AndroidManifest.xml, or the scheme field in an Expo app config), then teach your navigator how to turn paths into screens. In React Navigation that is the linking prop:

const linking = {
  prefixes: ['myapp://', 'https://example.com'],
  config: { screens: { Post: 'post/:id' } },
};

<NavigationContainer linking={linking}>{/* ... */}</NavigationContainer>;

Expo Router skips this step: every file is already a route, so every screen has a URL.

Under the hood the app receives URLs two ways, which the Linking API exposes: getInitialURL() when the link cold-starts the app, and a url event when the app is already running. Handling only one of them is the classic bug where links work "sometimes".

The misconception worth correcting: a custom scheme is not owned by you. Any app can register myapp://, and if your app is not installed the link simply fails. For links you share publicly, use verified https links instead: Universal Links on iOS and Android App Links. They open the app when installed and fall back to your website when not.

Test without building a sharing flow:

xcrun simctl openurl booted "myapp://post/42"
adb shell am start -W -a android.intent.action.VIEW -d "myapp://post/42"

Treat every deep link as untrusted input: validate parameters and require authentication before showing private screens.