So basically, you want to share an image via Facebook or Whatsapp, plus provide an option to save the image.
Well... Lets break this down slowly for the 2 quickest ways.
If you share image via UIActivityViewController then in order to provide Whatsapp option, you'll need to create a custom UIActivity (See Stackoverflow Question).
Whatsapp has not provided a URL scheme to pass an image object (yet).Look at JBWhatsAppActivity if you're curious about this in general.
If you share image via UIDocumentInteractionController then in order to provide the Facebook option, you'll need to specify the UTI as public.image.
The public.image UTI will populate your UIDocumentInteractionController with alot more options than just Facebook and Whatsapp.
You will need to use -presentOptionsMenuFromRect:inView:animated: method in order to show the option Save to Album. But this will include other options such as Mail etc.
If you use UIActivityViewController and don't want to create a custom UIActivity for Whatsapp, then you're stuck but... if you decide to use a custom UIActivity then you're still stuck because there's no provision to share an image object with Whatsapp using UIActivityViewController.
The thing that complicates it is Whatsapp which forces you to use UIDocumentInteractionController which seems like the only way to share an image on Whatsapp (currently) and due to it's limited URL scheme, there's no point providing it in UIActivityViewController.
Furthermore, using UIDocumentInteractionController in turns leads you to provide more options than you would want.
So I will leave the app just as it is, it works fine sharing for whatsapp, but not the way I wanted. Anyway, thanks for solving my doubt!
@LucasDomene : you're welcome :) well... right now i see no other way around it so you're better off the way you are.