iCloud data syncing, especially with Core Data, has become the bane of many an iOS developer’s existence. I can’t tell you how many developers have run into major issues implementing sync with Apple’s iCloud, no, really, I can’t tell you as most of them won’t go on the record. But there are quite a few.

One of those developers is Black Pixel, who we’ve covered here before several times. After purchasing the beloved RSS reader NetNewsWire in 2011, Black Pixel set about rebuilding it as a client for the Mac and iOS. And, like good soldiers, they were determined to use Apple’s new iCloud data syncing methods to keep it up to date across devices and platforms. Unfortunately, they ran into a snag. iCloud core data syncing just isn’t very good.

In the wake of the announcement that Google Reader is done for, the lack of a modern, updated NetNewsWire for Apple’s various devices has become even more of a thorn. Black Pixel Founder Daniel Pasco notes that they’ve re-written NetNewsWire from the ground up for the iPhone and iPad over the last year. In a blog post today, Pasco says that future versions of NetNewsWire will have sync, but it won’t be done with iCloud:

As far as sync is concerned, we knew we would likely need an alternative to Google Reader as early as last year. At the time, the option that seemed to make the most sense was to embrace iCloud and Core Data as the new sync solution of choice. We spent a considerable amount of time on this effort, but iCloud and Core Data syncing had issues that we simply could not resolve.

iCloud hasn’t worked out for us and Google’s announcement solidified and accelerated our plans.

The exact issues that Black Pixel ran into implementing iCloud aren’t detailed in the post, but I can tell you that it’s a sticking point for many. The Podcast app Instacast recently also divested itself of iCloud data sync. iCloud issues I’ve heard complained about by developers include  incoherent or nonexistent framework documentation as well as an overall lack of maturity on behalf of the protocol.

But Black Pixel is a very high-profile developer in the Mac community, and recently hired on some very talented staff including the returning Ex-Square product designer Chris Clark and Apple developer evangelist Michael Jurewitz. Having developers like Black Pixel ‘rage quit’ integration of iCloud Data Sync doesn’t say a lot about the maturity of the system, and it’s becoming a real problem for Apple.

As Pocket developer Steve Streza (who wrote a smart thing about app sync here) puts it, ”Remember that [Black Pixel] has many of the brightest people in Cocoa development. If they couldn’t get iCloud working, who can?”

Image Credit: Justin Sullivan/Getty Images