I did some research but seems still no luck
when I added these xml in my info.plist
UTImportedTypeDeclarations
It all depends on how "share" button in the host app is implemented. In iOS8, there are actually two different ways to do this: (1) using CFBundleDocumentTypes in Info.plist, and (2) Application Extension. Some apps such as GMail & AVR support both (1) & (2). But Dropbox supports (2) only. That's why CFBundleDocumentTypes does not work in Dropbox anymore. Of course, things may change later.