iphone - how can i assign application to open mail attachment -

hi want ios app should open exact format of attachment received mail. receive email attachment, open , click long attachment , want see option open app.

how can done?

use document interaction controller

http://developer.apple.com/library/ios/#documentation/uikit/reference/uidocumentinteractioncontroller_class/reference/reference.html#//apple_ref/doc/uid/tp40009304

"for example, email program might use class allow user preview attachments , open them in other apps. ..."