One of the long-standing advantages that Android has over iOS is that you can pick and choose different pieces of software to replace core system components like the app launcher and the software keyboard. Apple keeps these apps out of its store and offers no APIs for developers who want to create alternatives—if you want to use Apple's hardware and operating system, it's an all-or-nothing proposition.

The developers of Fleksy want to change that. There's now a public SDK for the alternative keyboard, giving developers what they need to replace Apple's keyboard with the Fleksy keyboard within their apps. You can download the standalone Fleksy app to give the keyboard a try for yourself—it offers several features that Apple's keyboard doesn't, including some convenient gesture controls and different color schemes. It looks like users who want to use the Fleksy keyboard in Fleksy-enabled apps will need to have this standalone app installed beforehand.

It's nice to see alternative iOS keyboards available in some applications (SwiftKey offers a similar note-taking app that adds its own keyboard improvements to Apple's), but Apple's restrictions mean they all have to fight an uphill battle. None of these keyboards can serve as a system-wide replacements—any of Apple's software will only use Apple's keyboards, and other developers would need to add support for Fleksy to each of their apps individually. Apple CEO Tim Cook has made some comments in the past about opening up iOS' APIs, but the company will continue to be cautious about this.

"I think you'll see us open up more [APIs] in the future, but not to the degree that we put the customer at risk of having a bad experience," Cook said at the AllThingsD conference last year. "There's always a fine line to walk there—or maybe not so fine in some cases."