How do I restrict document types using the iOS 8 Document Picker?

Thanks for the confirmation. So when the app gets updated then this will just work for my customers? In the mean time I've put in a file type check that I do after the user has downloaded the file to tell them if it's the right file type or not. Not very elegant, but it works.

Further to this, is it possible to restrict the Dropbox folder that's initially displayed via the UIDocumentPickerViewController? Like say if I want to show the contents of a subfolder instead of the root folder.