Good move on Microsoft's part…except that I don't think users really want more Office 365 in their lives.

"As part of our collaborative efforts to make the Office 365 APIs as seamless and easy as possible for mobile developers, Microsoft Open Technologies is launching an iOS SDK and releasing a new version of the Android SDK. These SDKs supplement the Visual Studio SDK that we have for developers. The iOS SDK supports Objective-C, with Swift support coming soon."

Office 365 email signature is a centralized web based signature service. It works with iOS and Android SDK. Tested on both, it works well.