capacitor-deep-linking

Deep Linking in Capacitor

Implement deep links, universal links, and app links in Capacitor apps.

When to Use This Skill

• User wants deep links
• User needs universal links
• User asks about URL schemes
• User wants to open app from links
• User needs share links

Types of Deep Links

Type	Platform	Format	Requires Server
Custom URL Scheme	Both	myapp://path	No
Universal Links	iOS	https://myapp.com/path	Yes
App Links	Android	https://myapp.com/path	Yes

Quick Start

Install Plugin

npm install @capacitor/app
npx cap sync

Handle Deep Links

import { App } from '@capacitor/app';

// Listen for deep link opens
App.addListener('appUrlOpen', (event) => {
  console.log('App opened with URL:', event.url);

  // Parse and navigate
  const url = new URL(event.url);
  handleDeepLink(url);
});

function handleDeepLink(url: URL) {
  // Custom scheme: myapp://product/123
  // Universal link: https://myapp.com/product/123

  const path = url.pathname || url.host + url.pathname;

  // Route based on path
  if (path.startsWith('/product/')) {
    const productId = path.split('/')[2];
    navigateTo(`/product/${productId}`);
  } else if (path.startsWith('/user/')) {
    const userId = path.split('/')[2];
    navigateTo(`/profile/${userId}`);
  } else if (path === '/login') {
    navigateTo('/login');
  } else {
    navigateTo('/');
  }
}

Custom URL Scheme

iOS Configuration

<!-- ios/App/App/Info.plist -->
<key>CFBundleURLTypes</key>
<array>
    <dict>
        <key>CFBundleURLName</key>
        <string>com.yourcompany.yourapp</string>
        <key>CFBundleURLSchemes</key>
        <array>
            <string>myapp</string>
            <string>myapp-dev</string>
        </array>
    </dict>
</array>

Android Configuration

<!-- android/app/src/main/AndroidManifest.xml -->
<activity android:name=".MainActivity">
    <!-- Deep link intent filter -->
    <intent-filter>
        <action android:name="android.intent.action.VIEW" />
        <category android:name="android.intent.category.DEFAULT" />
        <category android:name="android.intent.category.BROWSABLE" />

        <data android:scheme="myapp" />
    </intent-filter>
</activity>

Test Custom Scheme

# iOS Simulator
xcrun simctl openurl booted "myapp://product/123"

# Android
adb shell am start -a android.intent.action.VIEW -d "myapp://product/123"

Universal Links (iOS)

1. Enable Associated Domains

In Xcode:

1. Select App target
2. Signing & Capabilities
3. • Capability > Associated Domains
4. Add: applinks:myapp.com

2. Create apple-app-site-association

Host at https://myapp.com/.well-known/apple-app-site-association:

{
  "applinks": {
    "apps": [],
    "details": [
      {
        "appID": "TEAMID.com.yourcompany.yourapp",
        "paths": [
          "/product/*",
          "/user/*",
          "/invite/*",
          "NOT /api/*"
        ]
      }
    ]
  }
}

Requirements:

• Served over HTTPS
• Content-Type: application/json
• No redirects
• File at root domain

3. Info.plist

<!-- ios/App/App/Info.plist -->
<key>com.apple.developer.associated-domains</key>
<array>
    <string>applinks:myapp.com</string>
    <string>applinks:www.myapp.com</string>
</array>

Verify Universal Links

# Validate AASA file
curl -I https://myapp.com/.well-known/apple-app-site-association

# Check Apple CDN cache
curl "https://app-site-association.cdn-apple.com/a/v1/myapp.com"

App Links (Android)

1. Create assetlinks.json

Host at https://myapp.com/.well-known/assetlinks.json:

[
  {
    "relation": ["delegate_permission/common.handle_all_urls"],
    "target": {
      "namespace": "android_app",
      "package_name": "com.yourcompany.yourapp",
      "sha256_cert_fingerprints": [
        "AA:BB:CC:DD:EE:FF:00:11:22:33:44:55:66:77:88:99:AA:BB:CC:DD:EE:FF:00:11:22:33:44:55:66:77:88:99"
      ]
    }
  }
]

Get SHA256 Fingerprint

# Debug keystore
keytool -list -v -keystore ~/.android/debug.keystore -alias androiddebugkey -storepass android -keypass android

# Release keystore
keytool -list -v -keystore release.keystore -alias your-alias

# From APK
keytool -printcert -jarfile app-release.apk

2. AndroidManifest.xml

<!-- android/app/src/main/AndroidManifest.xml -->
<activity android:name=".MainActivity">
    <!-- App Links intent filter -->
    <intent-filter android:autoVerify="true">
        <action android:name="android.intent.action.VIEW" />
        <category android:name="android.intent.category.DEFAULT" />
        <category android:name="android.intent.category.BROWSABLE" />

        <data android:scheme="https" />
        <data android:host="myapp.com" />
        <data android:pathPrefix="/product" />
        <data android:pathPrefix="/user" />
        <data android:pathPrefix="/invite" />
    </intent-filter>
</activity>

Verify App Links

# Validate assetlinks.json
curl https://myapp.com/.well-known/assetlinks.json

# Use Google's validator
https://developers.google.com/digital-asset-links/tools/generator

# Check link handling on device
adb shell pm get-app-links com.yourcompany.yourapp

Advanced Routing

React Router Integration

import { App } from '@capacitor/app';
import { useHistory } from 'react-router-dom';
import { useEffect } from 'react';

function DeepLinkHandler() {
  const history = useHistory();

  useEffect(() => {
    App.addListener('appUrlOpen', (event) => {
      const url = new URL(event.url);
      const path = getPathFromUrl(url);

      // Navigate using React Router
      history.push(path);
    });

    // Check if app was opened with URL
    App.getLaunchUrl().then((result) => {
      if (result?.url) {
        const url = new URL(result.url);
        const path = getPathFromUrl(url);
        history.push(path);
      }
    });
  }, []);

  return null;
}

function getPathFromUrl(url: URL): string {
  // Handle both custom scheme and https
  if (url.protocol === 'myapp:') {
    return '/' + url.host + url.pathname;
  }
  return url.pathname + url.search;
}

Vue Router Integration

import { App } from '@capacitor/app';
import { useRouter } from 'vue-router';
import { onMounted } from 'vue';

export function useDeepLinks() {
  const router = useRouter();

  onMounted(async () => {
    App.addListener('appUrlOpen', (event) => {
      const path = parseDeepLink(event.url);
      router.push(path);
    });

    const launchUrl = await App.getLaunchUrl();
    if (launchUrl?.url) {
      const path = parseDeepLink(launchUrl.url);
      router.push(path);
    }
  });
}

Deferred Deep Links

Handle links when app wasn't installed:

import { App } from '@capacitor/app';
import { Preferences } from '@capacitor/preferences';

// On first launch, check for deferred link
async function checkDeferredDeepLink() {
  const { value: isFirstLaunch } = await Preferences.get({ key: 'firstLaunch' });

  if (isFirstLaunch !== 'false') {
    await Preferences.set({ key: 'firstLaunch', value: 'false' });

    // Check with your attribution service
    const deferredLink = await fetchDeferredLink();
    if (deferredLink) {
      handleDeepLink(new URL(deferredLink));
    }
  }
}

Query Parameters

App.addListener('appUrlOpen', (event) => {
  const url = new URL(event.url);

  // Get query parameters
  const source = url.searchParams.get('source');
  const campaign = url.searchParams.get('campaign');
  const referrer = url.searchParams.get('ref');

  // Track attribution
  analytics.logEvent('deep_link_open', {
    path: url.pathname,
    source,
    campaign,
    referrer,
  });

  // Navigate with state
  navigateTo(url.pathname, {
    state: { source, campaign, referrer },
  });
});

OAuth Callback Handling

// Handle OAuth redirect
App.addListener('appUrlOpen', async (event) => {
  const url = new URL(event.url);

  if (url.pathname === '/oauth/callback') {
    const code = url.searchParams.get('code');
    const state = url.searchParams.get('state');
    const error = url.searchParams.get('error');

    if (error) {
      handleOAuthError(error);
      return;
    }

    if (code && validateState(state)) {
      await exchangeCodeForToken(code);
      navigateTo('/home');
    }
  }
});

Testing

Test Matrix

Scenario	Command
Custom scheme	myapp://path
Universal link cold start	Tap link with app closed
Universal link warm start	Tap link with app in background
Universal link in Safari	Type URL in Safari
App link cold start	Tap link with app closed
App link in Chrome	Tap link in Chrome

Debug Tools

# iOS: Check associated domains entitlement
codesign -d --entitlements - App.app | grep associated-domains

# iOS: Reset Universal Links cache
xcrun simctl erase all

# Android: Check verified links
adb shell dumpsys package d | grep -A5 "Package: com.yourcompany.yourapp"

Common Issues

Issue	Solution
Universal Links not working	Check AASA file, SSL, entitlements
App Links not verified	Check assetlinks.json, fingerprint
Links open in browser	Check intent-filter, autoVerify
Cold start not handled	Use App.getLaunchUrl()
Simulator issues	Reset simulator, rebuild app

Resources

• Capacitor App Plugin: https://capacitorjs.com/docs/apis/app
• Universal Links Guide: https://developer.apple.com/documentation/xcode/supporting-universal-links-in-your-app
• Android App Links: https://developer.android.com/training/app-links
• Digital Asset Links Validator: https://developers.google.com/digital-asset-links/tools/generator