Talk to Spotify, and the company will claim that Apple is trying to strong-arm the service and push the agenda of its own streaming service, Apple Music, by blocking Spotify from releasing a new version of its app.

Talk to Apple, and the story is a bit different. No, the company isn't trying to unfairly punish Spotify for competing against Apple. It's simply enforcing App Store submission guidelines that Spotify -- according to Apple, at leat -- is violating. (And Apple also seems a bit irked that Spotify seems to be fighting its battle in the press.)

Spotify fired off its initial salvo against Apple in the form of a letter Spotify general counsel Horacio Gutierrez sent to Apple general counsel Bruce Sewell a few days ago. In it, as Recode reported, Gutierrez argued that Apple was "causing grave harm to Spotify and its customers" by rejecting the company's latest app update.

"This latest episode raises serious concerns under both U.S. and EU competition law. It continues a troubling pattern of behavior by Apple to exclude and diminish the competitiveness of Spotify on iOS and as a rival to Apple Music, particularly when seen against the backdrop of Apple's previous anticompetitive conduct aimed at Spotify -- we cannot stand by as Apple uses the App Store approval process as a weapon to harm competitors," Gutierrez wrote.

Apple's Sewell has since fired back a retort, claiming that Spotify has itself to blame for Apple rejecting its app's latest update. The primary issue revolves around in-app purchases -- specifically, that Apple reserves the right to make a commission from those made, and that developers can't just replace in-app purchases with other systems meant to cut Apple out of the deal entirely.

"Shortly after Spotify submitted its app on May 26, our team identified a number of issues, including that the in-app purchase feature had been removed and replaced with an account sign-up feature clearly intended to circumvent Apple's in-app purchase rules. That feature exists only for the purpose of avoiding having to pay Apple for your use of the App Store by emailing customers within hours, directing them to subscribe to Spotify on its website. A clear violation of the terms every other developer adheres to," Sewell wrote, as reported by Buzzfeed.

"During a number of discussions between our team and Spotify, we explained why this sign-up feature did not comply with our guidelines and requested you resubmit a compliant version of the app. On June 10, Spotify submitted another version of the app which again incorporated the sign-up feature directing App Store customers to submit an email address so they could be contacted directly by Spotify in a continued attempt to get around our guidelines. Spotify's app was again rejected for attempting to circumvent in-app purchase rules, and not, as you claim, because Spotify was simply seeking to communicate with its customers."

Spotify has yet to respond to Apple's response, and we don't yet know just what Spotify is planning to do with its proposed app update. We sense the company will have to capitulate to Apple, lest it find itself unable to launch any new Spotify features for iOS users -- not a great way to generate goodwill among Apple's user base.

According to Sewell, Apple is happy to expedite Spotify's update through the review and approval process "as soon as you provide us with something that is compliant with the App Store's rules."