FileMaker iOS App SDK 15.0.2
Sadly the 15.0.2 SDK has a little change. The updateProjectSettings utility used in the Xcode project overwrites the RequiredToLink.mm file each time. But in this file we put our initialization call for our static library. This breaks the extension.
To fix it, please rename the RequiredToLink.mm file in the project. For example name it "MyRequiredToLink.mm". After the change is made, the file is no longer overwritten and you can enjoy our extension.
And someday we hope to see plugin support in FileMaker iOS SDK and offer our plugin for iOS. I already have one compiled here...