@ccatto/capacitor-inapp-auth

A tiny Capacitor plugin that wraps ASWebAuthenticationSession so an OAuth flow (Google / Apple / Facebook) can run in the system browser from inside a native app and return via a custom URL scheme.

Why

• OAuth providers block embedded webviews (disallowed_useragent), so OAuth must use the system browser.
• SFSafariViewController (what @capacitor/browser opens) silently blocks redirect navigation to custom schemes (myapp://…) — the sheet just hangs.
• ASWebAuthenticationSession is Apple's purpose-built API: it captures the registered callback scheme, dismisses the sheet, and hands the URL back to JS.

Install

npm install @ccatto/capacitor-inapp-auth
npx cap sync ios

Usage

import { InAppAuth } from '@ccatto/capacitor-inapp-auth';
import { Capacitor } from '@capacitor/core';

if (Capacitor.isPluginAvailable('InAppAuth')) {
  const { url } = await InAppAuth.start({
    url: 'https://yourapp.com/api/mobile-social-start?provider=google',
    callbackScheme: 'myapp', // must match a CFBundleURLSchemes entry in Info.plist
  });
  // url === 'myapp://auth-callback?code=…'
  const code = new URLSearchParams(url.split('?')[1]).get('code');
}

start() rejects with code "CANCELED" if the user dismisses the sheet.

iOS setup

1. Register your scheme in Info.plist under CFBundleURLTypes → CFBundleURLSchemes (e.g. myapp).
2. The plugin conforms to CAPBridgedPlugin (required for Capacitor 6+ registration) and targets iOS 14+.

Notes

• iOS only today. On web, start() throws unavailable — use the standard OAuth redirect flow there.
• The server flow that pairs with this plugin (a mobile-social-start route that initiates OAuth server-side and a mobile-auth-callback route that 302s to myapp://…) lives in the consuming app; see @ccatto/react-auth.