The official word is in. On September 28, a spokesperson emailed the following statement, attributable to Chris Wolfe, Director Product Management at SwiftKey:
"As of October 5, support for SwiftKey iOS will end and it will be delisted from the Apple App Store. Microsoft will continue support for SwiftKey Android as well as the underlying technology that powers the Windows touch keyboard. For those customers who have SwiftKey installed on iOS, it will continue to work until it is manually uninstalled or a user gets a new device. Please visit Support.SwiftKey.com for more information."
I asked for the official reason why Microsoft had made this decision and was told officials had nothing more to say.
I'm guessing the decision had as much to do with Apple's policies around safeguarding its walled garden as anything. The Microsoft Phone Link team knows well that if Apple doesn't grant access to certain interfaces, there's no easy or good way to make a product which needs integration to work.
Microsoft bought SwiftKey in 2016. At the time, Microsoft was on a buying spree, snapping up companies with strong iOS and Android presence in order to give Microsoft at least some kind of foothold in the mobile phone space. At the time it acquired SwiftKey, Microsoft officials said the keyboard and SDK-powered services were used on more than 300 million Android and iOS devices. From 2012 to 2013, SwiftKey was the best-selling paid app on Google Play.
SwiftKey is a free predictive keyboard app meant to help mobile users type faster. It uses an algorithm, built by analyzing large amounts of text, to predict what you are trying to type, and what you will want to type next using AI/natural language processing technology.
Microsoft is planning to continue to support SwiftKey on Android for the foreseeable future.