The chocolate bar-themed KitKat 4.4 (formerly Key Lime Pie) is expected to arrive later this year and possibly as soon as later this month. Information about it is gradually trickling out, with likely features including better support for wireless printing from Android devices and possibly native NFC payment options, rather than only third-party enabled capabilities.
Google said in a post on its Android Developer blog that, while many developers have built apps to improve on the texting experience on Android, some of these have been created using hidden APIs, which Google doesn't like because they can be changed or removed without warning, and can't be tested for compatibility with new devices.
In order to make the user experience for messaging "more predictable", Android 4.4 KitKat is making the existing SMS APIs public and adds the concept of a default SMS app, "which the user can select in system settings".
As a result, developers using hidden APIs will have to make some change for their app to continue to work when Android 4.4 is released, Google said.
"As such, it's important that you update your messaging app as soon as possible to be available as a default SMS app, because although your existing app won't crash on an Android 4.4 device, it will silently fail when attempting to write to the SMS Provider," it said.
"When your app is not currently selected as the default SMS app, it's important that you disable the ability to send new messages from your app because, without the ability to write to the SMS Provider, any messages you send won't be visible in the user's default SMS app."