This is kind of confusing. When I cloned this fork locally, I get a warning on this line. Auto-fix says it should be ``%d``.
``NSData length``'s signature is ``- (NSUInteger)length``.

Do you have any special settings with your dev environment? What platform are you targeting? What version of Xcode are you on?
I'm wondering why I'm not seeing the same warnings as you are?