One week after it was unceremoniously booted from Apple's iOS App Store, 500px has returned. The app is once again available for both iPhone and iPad after it was pulled down last Monday. In a statement at the time, Apple explained that the 500px takedown came as a direct result of the app "featuring pornographic images and material, a clear violation of our guidelines." The company even claimed that it had received complaints of child pornography within the photography app. However, it appears both sides have worked through the issue.

Judging by the latest release notes, it doesn't seem 500px has made many significant changes to the app, nor stripped away existing functionality. It has, however, added a new "report" button that lets users easily flag inappropriate content. Whether that was enough to gain Apple's approval or if there are other, less obvious changes is currently unclear. We've reached out to 500px for details. Unfortunately, while photo enthusiasts can once again download 500px from the App Store as of today, Apple's troubling porn problem remains.

Update: Since the app went back up, we've talked to 500px co-founder Evgeny Tchebotarev about the changes that Apple required to put it back in the store. In addition to the "report" button, which Tchebotarev says Apple requested, the company has tweaked its search to make it harder for potentially offending photos to show up based on suggestive keywords (users who have opted into adult images on 500px's site will not be affected.) Most significantly, however, the rating has been raised, allegedly at Apple's behest: it's now 17+, the highest age rating on iTunes.

Tchebotarev draws a connection to the controversy over porn on Vine, which has been pulled from Apple's "Editor's Choice" list but remains up with a 12+ rating; the Twitter-owned service has far more clout than the smaller 500px. "If you look at other apps like Vine," he says, "they don't necessarily have the same rating we do." He also says that while his team is investigating Apple's child pornography allegations, he hasn't found anything yet. "We're still waiting to see the images or complaints that Apple received. We did our own internal audit, and we found no pornographic images on our platform."

Adi Robertson contributed to this report.