Pull-to-refresh is a handy feature that you’ll find in several iOS apps, like Tweetbot, Sparrow, and Facebook. It would make sense then for Apple to include such useful functionality in its own apps, like Mail, but it turns out that Twitter put forward a patent application for the feature back in 2010 that may be preventing Apple from doing so.
The patent is titled “User Interface Mechanics”, with the inventor listed as Loren Brichter, the creator of Tweetie. Tweetie was acquired by Twitter back in April 2010, with this patent being filed in August 2010. The patent details how “a scrollable refresh trigger may be displayed”, which would then lead to a refreshed “list of content items”.
When Paul Haddad, a member of the team behind TweetBot, was asked about the patent, he said that “Every large software company has large piles of patents, most of dubious merit. Most use them as a purely defensive measure,” adding “Twitter is remarkably good at contributing opensource, some impressive stuff too. Patent attacks from them aren't something I worry about.”
Loren Brichter stated back when the patent was first filed that he would not enforce it against those implementing the same functionality into other apps. As Haddad stated, most companies use patents defensively as well as offensively, so it’s unlikely that Twitter would start a crusade against those using the pull-to-refresh feature.