cap-go/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