Overview

In your Podfile, add the dependency for the PayPal Mobile Checkout module:

pod 'Braintree/PayPal'

Carthage

Include the BraintreeCore, BraintreePayPal and PayPalDataCollector frameworks.

An example apple-app-site-associationhandle may look like the following:

Register Universal Link in Control Panel

Before using this feature, you must register your Universal Link domain in the Braintree Control Panel:

• Log into your Control Panel (e.g. Sandbox, or Production).
• Click on the gear icon in the top right corner. A drop-down menu will open.
• Click Account Settings from the drop-down menu.
• Scroll to the Payment Methods section.
• Next to PayPal, click the Options link. This will take you to your linked PayPal Account(s) page.
• Click the View Domain Names button. This will take you to the PayPal Domain Names page.
• Note: If you have a single PayPal account, it will be at the bottom of the page. If you have multiple PayPal accounts, it will be at the top right of the page.
• Click the + Add link on the top right of the page or scroll to the Specify Your Domain Names section.
• In the text box enter your list of domain names separated by commas.
• Note: The value you enter must match your fully qualified domain name exactly – including the "www." if applicable.
• Click the Add Domain Names button.
• If the domain registration was successful for all the domain names listed in the text box, a banner will display the text "Successfully added domains". The registered domain names will be displayed in alphabetical order under the + Add button.
• If the registration was not successful for any of the domain names listed in the text box, a banner will display a list of domain names that failed qualified domain name validation along with their reasons for rejection. Any domain names that were successfully registered will be displayed in alphabetical order under the + Add button.
• Note: You can re-enter the rejected domain names in the text area with the corrections applied.

Set Universal Link in SDK

You will need to use the following BTPayPalClient init to set your Universal Link:

let apiClient = BTAPIClient(authorization: <#CLIENT_AUTHORIZATION#>)
let payPalClient = BTPayPalClient(
  apiClient: apiClient, // required
  universalLink: URL(string: "https://my-universal-link.com/braintree-payments")! // required
)

Handle App Context Switching

Then pass the URL to Braintree for completion of the flow.

If you're using SwiftUI, you must add the onOpenURL(perform:) modifier to your ContentView, and then call BTAppContextSwitcher'shandleOpen(_:) method.

.onOpenURL { url in
  BTAppContextSwitcher.sharedInstance.handleOpen(url)
}

If you're using UISceneDelegate (introduced in iOS 13), call the handleOpen(_:) method from within the scene(_:continue:) scene delegate method.

func scene(_ scene: UIScene, continue userActivity: NSUserActivity) {
  if let returnURL = userActivity.webpageURL, returnURL.path.contains("/my-dedicated-braintree-path") {
    BTAppContextSwitcher.sharedInstance.handleOpen(returnURL)
  }
}

Otherwise, if you aren't using UISceneDelegate, call the handleOpen(_:) method method from within the application(_:continue:restorationHandler:) app delegate method.

func application(_ application: UIApplication, continue userActivity: NSUserActivity, restorationHandler: @escaping ([UIUserActivityRestoring]?) -> Void) -> Bool {
  if let returnURL = userActivity.webpageURL, returnURL.path.contains("/my-dedicated-braintree-path") {
    BTAppContextSwitcher.sharedInstance.handleOpen(returnURL)
  }
}

Invoking the PayPal App Switch flow

Opt in to the App Switch flow

Construct a BTPayPalVaultRequest or a BTPayPalCheckoutRequest with enablePayPalAppSwitch set to true and a userAuthenticationEmail included. Use this with your BTPayPalClient from above to call BTPayPalClient.tokenize(_:completion:) to launch the PayPal App Switch flow.

An example integration might look like this:

import UIKit
import BraintreePayPal

class MyViewController: UIViewController {
  var apiClient: BTAPIClient!
  var payPalClient: BTPayPalClient!
  let payPalButton = UIButton(type: .system)

  override func viewDidLoad() {
    super.viewDidLoad()
    apiClient = BTAPIClient(authorization: <#CLIENT_AUTHORIZATION#>)
    payPalClient = BTPayPalClient(
      apiClient: apiClient, 
      universalLink: universalLink: URL(string: "https://my-universal-link.com/braintree-payments")! // required for this flow
    )
    setUpButton()
  }

   private func setUpButton() {
    payPalButton.translatesAutoresizingMaskIntoConstraints = false
    payPalButton.setTitle("PayPal Checkout", for: .normal)
    payPalButton.setTitleColor(.blue, for: .normal)
    payPalButton.addTarget(self, action: #selector(payPalButtonTapped), for: .touchUpInside)
    view.addSubview(payPalButton)
  }

  @objc func payPalButtonTapped(_ sender: UIButton) {
    sender.isEnabled = false

    // one time checkout flows
    let request = BTPayPalCheckoutRequest(
      amount: amount
      userAuthenticationEmail: "sally@gmail.com",
      enablePayPalAppSwitch: true
    )
    
    // userAuthenticationEmail and enablePayPalAppSwitch are required for this flow
    // Configure other values on 'request' as needed.

    payPalClient.tokenize(request) { payPalNonce, error in
      sender.isEnabled = true
      if let payPalNonce { 
        // send payPalNonce.nonce to server 
      } else { 
        // handle error
      }
    }
  }
}