The app code signing process provides some assurance that the app has not been altered. https://developer.apple.com/library/mac/documentation/Security/Conceptu

The app code signing process provides some assurance that the app has not been altered. https://developer.apple.com/library/mac/documentation/Security/Conceptual/CodeSigningGuide/Introduction/Introduction.html https://developer.apple.com/library/mac/documentation/Securi... edit: but only in so much as you trust Apple, as they provide and verify the keys. But... assuming you're using an iphone, this isn't really a new threat vector.