PopupBridge is an iOS library that allows WKWebViews to open popup windows in an ASWebAuthenticationSession browser and send data back to the parent page in the WKWebView.
PopupBridge is also available for Android.
See the Frequently Asked Questions to learn more about PopupBridge. See Using PayPal in a WebView to use PopupBridge with PayPal.
- iOS 16.0+
- Xcode 16.2.0+
- Swift 5.10+, or Objective-C
To integrate using CocoaPods, add the following line to your Podfile:
pod 'PopupBridge'To integrate using Carthage, add github "braintree/popup-bridge-ios" to your Cartfile, and add the frameworks to your project.
To integrate using Swift Package Manager, select File > Swift Packages > Add Package Dependency and enter https://github.com/braintree/popup-bridge-ios as the repository URL. Tick the checkbox for PopupBridge.
If you look at your app target, you will see that PopupBridge is automatically linked as a framework to your app (see General > Frameworks, Libraries, and Embedded Content).
You must add the following to the queries schemes allowlist in your app's info.plist:
<key>LSApplicationQueriesSchemes</key>
<array>
<string>com.venmo.touch.v2</string>
</array>To run the sample app, clone the repo, open PopupBridge.xcworkspace and run the Demo app target.
-
Integrate PopupBridge with your WKWebView:
class ViewController: UIViewController { var webView: WKWebView = WKWebView(frame: CGRect(x: 0, y: 0, width: 300, height: 700)) var popupBridge: POPPopupBridge? override func viewDidLoad() { super.viewDidLoad() view.addSubview(webView) popupBridge = POPPopupBridge(webView: webView) // Replace http://localhost:3099/ with the webpage you want to open in the webview let url = URL(string: "http://localhost:3099/")! webView.load(URLRequest(url: url)) } }
<!-- From https://developer.paypal.com/braintree/docs/guides/paypal/client-side/javascript/v3/ -->
<head>
<!-- Load the client component. -->
<script src="https://js.braintreegateway.com/web/3.117.1/js/client.min.js"></script>
<!-- Load the PayPal Checkout component. -->
<script src="https://js.braintreegateway.com/web/3.117.1/js/paypal-checkout.min.js"></script>
</head>
<body>
<div id="paypal-button"></div>
</body>// From https://developer.paypal.com/braintree/docs/guides/paypal/client-side/javascript/v3/
if (!window.popupBridge) {
throw new Error("Popup Bridge is is not installed!");
}
// Create a client.
braintree.client.create({
authorization: CLIENT_AUTHORIZATION
}).then(function (clientInstance) {
// Create a PayPal Checkout component.
return braintree.paypalCheckout.create({
client: clientInstance
});
}).then(function (paypalCheckoutInstance) {
// Load the PayPal JS SDK (see Load the PayPal JS SDK section)
paypalCheckoutInstance.loadPayPalSDK().then(function () {
// The PayPal script is now loaded on the page and
// window.paypal.Buttons is now available to use
// render the PayPal button (see Render the PayPal Button section)
});
}).catch(function (err) {
// Handle component creation error
});<!-- From https://developer.paypal.com/braintree/docs/guides/venmo/client-side/javascript/v3/ -->
<head>
<script src="https://js.braintreegateway.com/web/3.117.1/js/client.min.js"></script>
<script src="https://js.braintreegateway.com/web/3.117.1/js/venmo.min.js"></script>
<script src="https://js.braintreegateway.com/web/3.117.1/js/data-collector.min.js"></script>
</head>
<body>
<div id="venmo-button"></div>
</body>// From https://developer.paypal.com/braintree/docs/guides/venmo/client-side/javascript/v3/
if (!window.popupBridge) {
throw new Error("Popup Bridge is is not installed!");
} else {
// If using PopupBridge, set the deepLinkReturnUrl so that the Venmo app
// knows where to return after authorization. This ensures the app resumes
// correctly from the WebView.
// Note: When integrating with Venmo via WebView and PopupBridge, it's important to set the deepLinkReturnUrl
// so the user is redirected back to the correct context in your app after completing the flow in the Venmo app.
createOptions.deepLinkReturnUrl = window.popupBridge.getReturnUrlPrefix();
window.popupBridge.onComplete = (err, payload) => {
console.log('Popup Bridge completed');
if (err) {
console.log(err);
}
console.log(payload);
window.location.hash = payload.hash;
};
}
var venmoButton = document.getElementById('venmo-button');
braintree.venmo.create({
client: clientInstance,
allowDesktop: true,
mobileWebFallBack: true,
allowDesktopWebLogin: true,
paymentMethodUsage: 'multi_use'
// Add allowNewBrowserTab: false if your checkout page does not support
// relaunching in a new tab when returning from the Venmo app. This can
// be omitted otherwise.
// allowNewBrowserTab: false
}).then(function (venmoInstance) {
// Verify browser support before proceeding.
if (!venmoInstance.isBrowserSupported()) {
console.log('Browser does not support Venmo');
return;
}
displayVenmoButton(venmoInstance);
// Check if tokenization results already exist. This occurs when your
// checkout page is relaunched in a new tab. This step can be omitted
// if allowNewBrowserTab is false.
if (venmoInstance.hasTokenizationResult()) {
venmoInstance.tokenize().then(handleVenmoSuccess).catch(handleVenmoError);
}
}).catch(function (venmoErr) {
console.error('Error creating Venmo:', venmoErr);
});
function displayVenmoButton(venmoInstance) {
// Assumes that venmoButton is initially display: none.
venmoButton.style.display = 'block';
venmoButton.addEventListener('click', function () {
venmoButton.disabled = true;
venmoInstance.tokenize().then(function (payload) {
venmoButton.removeAttribute('disabled');
// ...
});
});
}
function handleVenmoError(err) {
// ...
}
function handleVenmoSuccess(payload) {
// ...
}WKWebView can open popups through its WKUIDelegate, which can be implemented to present the popup in a new WKWebView.
However, WKWebViews do not display an address bar or an HTTPS lock icon. If the popup receives sensitive user information (e.g. login credentials), users must implicitly trust that the web page is not redirecting them to a malicious spoofed page that may steal their information. PopupBridge solves this by using an ASWebAuthenticationSession.
- Apps with WebViews that need to open a popup
- When a popup window needs to to send data from the popup back to the WKWebView
- When the popup window needs to display the HTTPS lock icon to increase user trust
- Apps that use OAuth
- PopupBridge attaches to a WKWebView by injecting a user script to the page
- This exposes a JavaScript interface (via
window.popupBridge) for the web page to interact with the iOS code
- This exposes a JavaScript interface (via
- The web page detects whether the page has access to
window.popupBridge; if so, it creates a ASWebAuthenticationSession to open the popup URL- The web page can also use
popupBridge.onCompleteas a callback
- The web page can also use
- If the user taps the Cancel button on the ASWebAuthenticationSession,
popupBridge.onCompletegets called with the error and payload asnull
We are engineers who work on the Developer Experience team at Braintree.
Short answer: to accept PayPal as a payment option when mobile apps are using a WebView to power the checkout process.
PayPal authentication occurs in a popup window. However, this causes issues with Braintree merchants who use a web page to power payments within their apps: they can't accept PayPal because WebViews cannot open popups and return the PayPal payment authorization data to the parent checkout page.
PopupBridge solves this problem by allowing braintree-web or PayPal's Checkout.js to open the PayPal popup from a secure mini-browser.
WebView-based checkout flows can accept PayPal with PopupBridge and the Braintree JS SDK or PayPal's Checkout.js. For the authentication flow, PayPal requires a popup window—which can be simulated with PopupBridge.
- Create a web-based checkout that accepts PayPal using Checkout.js or the Braintree JS SDK
- Create a native mobile app that opens the checkout in a
WKWebView(See the quick start instructions) - Integrate the PopupBridge library
- Collect device data
- To help detect fraudulent activity, collect device data before performing PayPal transactions. This is similar to collecting device data with our native iOS SDK with a few differences:
- Rather than importing the entire data collector, you can add just PayPalDataCollector to your app:
pod 'Braintree/PayPalDataCollector' - Implement methods in your native app depending on whether you are doing one-time payments or vaulted payments. See the iOS code snippets for PayPal + PopupBridge
- Rather than importing the entire data collector, you can add just PayPalDataCollector to your app:
- To help detect fraudulent activity, collect device data before performing PayPal transactions. This is similar to collecting device data with our native iOS SDK with a few differences:
- Profit!
This SDK abides by our Client SDK Deprecation Policy. For more information on the potential statuses of an SDK check our developer docs.
| Major version number | Status | Released | Deprecated | Unsupported |
|---|---|---|---|---|
| 3.x.x | Active | April 2025 | TBA | TBA |
| 2.x.x | Inactive | October 2023 | April 2025 | April 2026 |
| 1.x.x | Inactive | 2016 | October 2024 | October 2025 |
Braintree, [email protected]
PopupBridge is available under the MIT license. See the LICENSE file for more info.