Link iOS SDK

The Plaid Link SDK is a quick and secure way to link bank accounts to Plaid from within your iOS app. LinkKit is a drop-in framework that handles connecting a financial institution to your app (credential validation, multi-factor authentication, error handling, etc.) without passing sensitive information to your server.

To get started with Plaid Link for iOS, clone the GitHub repository and try out the example application, which provides a reference implementation in both Swift and Objective-C. Youʼll want to sign up for free API keys through the Plaid Developer Dashboard to get started.

Before writing code using the SDK, you must first perform some setup steps to register your app with Plaid and configure your project.

1. Sign in to the Plaid Dashboard and go to the Team Settings -> API page.
2. Next to Allowed redirect URIs click Configure then Add New URI.
3. Enter your redirect URI, which you must also set up as a Universal Link for your application, for example: https://app.example.com/plaid/.
4. Click Save Changes.

These redirect URIs must be set up as Universal Links in your application. For details, see Apple's documentation on Allowing Apps and Websites to Link to Your Content.

In order for Plaid to return control back to your application after a user completes a bank's OAuth flow, you must specify a redirect URI, which will be the URI from which Link will be re-launched to complete the OAuth flow. The redirect URI must be a Universal Link. An example of a typical redirect URI is: https://app.example.com/plaid.

Universal Links consist of the following parts:

• An applinks entitlement for the Associated Domains capability in your app. For details, see Apple’s documentation on the Associated Domains Entitlement and the entitlements example in the LinkDemo-Swift example app.
• Code in your app handling the user activity when your app is opened via Universal Links. For details, see Apple's documentation on Supporting Universal Links in your app and the AppDelegate example in the LinkDemo-Swift example app. The Plaid Link SDK will ignore unexpected URLs passed to continue(from:) as per Apple’s recommendations, so there is no need to filter out unrelated URLs. Doing so may prevent a valid URL from being passed to continue(from:) and OAuth may not continue as expected.
• An apple-app-site-association file on your website. For details, see Apple’s documentation on Supporting Associated Domains and see our minimal example below.

There are a few requirements for apple-app-site-association files:

• Must be a static JSON file
• Must be hosted using a https:// scheme with a valid certificate and no redirects
• Must be hosted at https://<my-fully-qualified-domain>/.well-known/apple-app-site-association

Below is an example for https://my-app.com (https://my-app.com/.well-known/apple-app-site-association)

1{
2 "applinks": {
3     "details": [
4          {
5            "appIDs": [ "<My Application Identifier Prefix>.<My Bundle ID>" ],
6            "components": [
7              {
8                 "/": "/plaid/*",
9                 "comment": "Matches any URL path whose path starts with /plaid/"
10              }
11            ]
12          }
13      ]
14  }
15}

Once you have enabled Universal Links, your iOS app is now set up and ready to start integrating with the Plaid SDK.

Plaid Link for iOS is an embeddable framework that is bundled and distributed with your application. There are several ways to obtain the necessary files and keep them up-to-date; we recommend using Swift Package Manager or CocoaPods. Regardless of what you choose, submitting a new version of your application with the updated LinkKit.xcframework to the App Store is required.

New versions of LinkKit.xcframework are released frequently, at least once every few months. We recommend you keep up to date to provide the best Plaid Link experience in your application.

For details on each release see the GitHub releases and version release notes. To upgrade Plaid Link iOS from 1.x to 2.x, refer to the iOS 1.x to 2.x migration guide.

Before you can open Link, you need to first create a link_token. A link_token can be configured for different Link flows and is used to control much of Link’s behavior. To learn how to create a new link_token, see the API Reference entry for /link/token/create.

1var linkConfiguration = LinkTokenConfiguration(
2    token: "<#LINK_TOKEN_FROM_SERVER#>",
3    onSuccess: { linkSuccess in
4        // Send the linkSuccess.publicToken to your app server.
5    }
6)

A Handler is a one-time use object used to open a Link session. The Handler must be retained for the duration of the Plaid SDK flow. It will also be needed to respond to OAuth Universal Link redirects. For more details, see the OAuth guide.

1let result = Plaid.create(configuration)
2switch result {
3  case .failure(let error):
4      logger.error("Unable to create Plaid handler due to: \(error)")
5  case .success(let handler):
6      self.handler = handler
7}

Finally, open Link by calling open on the Handler object. This will usually be done in a button’s target action.

1let method: PresentationMethod = .viewController(self)
2handler.open(presentUsing: method)

When your app is opened via an Universal Link, it must check whether the opened URL is the redirect URI registered with Plaid and pass the URL to LinkKit to complete the account linking flow.

1if userActivity.activityType == NSUserActivityTypeBrowsingWeb, let redirectUri = userActivity.webpageURL {
2  // NOTE: Your handler must be accessible from your application delegate or scene delegate.
3  self.handler.continue(from: redirectUri)
4}

1onSuccess: { linkSuccess in
2  // Send the linkSuccess.publicToken to your app server.
3}

1linkConfiguration.onExit = { linkExit in
2  // Optionally handle linkExit data according to your application's needs
3}

1linkConfiguration.onEvent = { linkEvent in
2  // Optionally handle linkEvent data according to your application's needs
3}

Once you've gotten Link working, see Link best practices for recommendations on further improving the Link flow.