This is the official Payeezy iOS SDK to integrate payments, credit cards, and e-commerce solutions into Apple Pay. A PDF guide in GitHub published by Atul, the same writer of the SDK, demonstrates how to install, create payment tokens, and integrate with Apple Pay. Guide available at https://github.com/payeezy/payeezy_ios/blob/master/guide/payeezy_iOS_SDK042015.pdf
Square now has an E-commerce API that brings Square services to third party websites. Square is usually associated with its mobile credit card reader and complementary software. With the E-commerce API, merchants can use their own systems with all the benefit of Square's modern payment services.