Performing an in-app payment with Android Pay against Vantiv's eCommerce platform is relatively simple, but will require either the development of new native iOS applications or the modification of your existing applications.
Vantiv supports two methods for merchants to submit Android Pay transactions to our eCommerce platform. The first involved you sending certain Vantiv specific parameters to Google in return for a Vantiv paypageRegistrationId which you use normally in payment transactions with Vantiv. The second method involves the merchant receiving encrypted data from Google that needs to be be decrypted on your own servers before submitting a payment transaction to Vantiv.
Step by step details are provided in the Android Pay in-App for eCommerce sub-space.