You will not be able to use the iFlow Reader app for iOS after 31 May as it -- and the company that created it -- will be shutting down.

iFlow Reader is made by BeamItDown software but the company has announced that from the end of the month, it will cease operations. The company issued a damning statement, pointing the finger at Apple for the turn of events.

"We absolutely do not want to do this, but Apple has made it completely impossible for anyone but Apple to make a profit selling contemporary ebooks on any iOS device. We cannot survive selling books at a loss and so we are forced to go out of business," a statement on the iFlow Reader website reads.

"We bet everything on Apple and iOS and then Apple killed us by changing the rules in the middle of the game. This is a very sad day for innovation on iOS in this important application category. We are a small company that thought we could build a better product. We think that we did but we are powerless against Apple's absolute control of the iOS platform," it contined.

BeamItDown's grievance with Apple centres on the new in-app purchasing model, introduced in February. Apple requires app publishers that sell content within their apps - such as eBooks or individual editions of a newspaper or magazine - surrender 30 percent of the selling price.

According to BeamItDown, this is "not a sustainable business model". "Our gross margin on ebooks after paying the wholesaler is less than 30 percent, which means that we would have to take a loss on all ebooks sold," the company said.

"We sent a letter to Apple VP Philip Schiller in September 2009 to confirm our business model. Apple told us they couldn't guarantee anything - submit the application and they'd let us know after submission. We submitted our new iFlowReader app Apple in November of 2010 and they approved it a few days later.

"After approval, we made substantial additional investments in licensing fees, integration fees, and server fees so that we could open our ebook store on December 2, 2010. Two months later, Apple changed the rules and put us out of business. They now want 30% of the sale price of any books, which they know full well, is all of our profits and more."

It isn't just eBook sellers that have been affected by the new in-app purchase rules. Back in February, music services We7.com, Last.fm and Rhapsody complained about Apple's new policy.

We7's Steve Purdham said that Apple's subscription model was "economically unviable" whereas Last.fm co-founder Richard Jones was even more forthright, saying: "Apple just f****d over online music subs for the iPhone."

iFlow Reader users can download all titles they have purchased through the app onto their Mac or Windows PC - the company's website contains instructions on how to do so.