Apple denied that it changed its rules in any way or enforced them any differently for Sony, and that it instead was only looking to ensure that customers could buy books using its "in-app purchase" payment method, which provides Apple with a 30 percent cut of sales made.
The dust up doesn't appear to have affected Amazon.com however. Amazon offers a Kindle app through the App Store which lets users view books bought through Amazon on the Apple devices.
"We opened a dialogue with Apple to see if we can come up with an equitable resolution for both companies as well as our consumers, but reached an impasse at this time," Sony said in a statement on Tuesday. Developer guidelines from Apple state that apps using a different system to the in-app purchase to buy "content, functionality or services" will be rejected.