Yesterday, streaming music service Spotify went public with complaints that Apple had recently rejected an update to the company's iOS app. The company's lawyers alleged that blocking the update "raises serious concerns under both US and EU competition law" and "[diminishes] the competitiveness of Spotify on iOS and as a rival to Apple Music." But Spotify offered up only a vague explanation for why the app had been rejected, citing "business model rules."

Today, Apple General Counsel Bruce Sewell responded, saying that Spotify's app update violated Apple's app review guidelines and that the company would gladly approve and distribute the update once the problem had been fixed. The full letter is available in this Buzzfeed report.

"We're disappointed with the public attacks you've made and appreciate the opportunity to set the record straight," writes Sewell to Spotify General Counsel Horacio Gutierrez. "Our guidelines help competition, not hurt it. The fact that we compete has never influenced how Apple treats Spotify or other successful competitors like Google Play Music, Tidal, Amazon Music, Pandora, or the numerous other apps on the App Store that distribute digital music."

Specifically, Spotify has apparently violated rule 3.1.1 of Apple's App Store Review Guidelines, which states that apps may not provide external links or other text that invites users to subscribe to services through sites rather than Apple's own in-app purchase system. Apple says that Spotify's update replaced the previous in-app purchase option "with an account sign-up feature clearly intended to circumvent Apple's in-app purchase rules." Apple alerted Spotify of the problem, and Spotify apparently submitted a second version of the update that asked users "to submit an e-mail address so they could be contacted directly by Spotify."

The Android version of the Spotify app directs potential subscribers to Spotify's site via an in-app webview, similarly skirting around Google's own in-app purchasing option—Google won't reject an app from the Google Play Store on those grounds, though.

By repeatedly submitting apps that break Apple's rules and complaining publicly about the rejection, Sewell says that Spotify is asking for "preferential treatment" and "waivers and exemptions from the rules that pertain to all other developers on the App Store" whether Apple competes with those developers or not.

Spotify doesn't want users to sign up for the paid version of the service through the iOS app, because Apple takes a 30 percent cut of those subscription fees. If those people sign up on Spotify's site instead, they get the exact same features within the app, but Spotify keeps 100 percent of the money instead of 70 percent. For a while, Spotify compensated for Apple's cut by charging iOS subscribers $12.99 instead of the normal $9.99, but that option has been removed from the current version of the app. Apple will soon begin giving service providers an 85 percent cut of subscription fees once users have been signed up for a year, but the 70-30 split will still apply for new subscribers.