As stated on this post, there is a fix for this issue without downgrading. You only need to add Security and SystemConfiguration frameworks in "Build Phases"->"Link binary with libraries".

Fixed it. 

The problem is when you migrate the project from 5.2.x to 5.3.x - You're prompted to update certain APIs - this is the thing causing it to fail to compile.

The way to fix this, is by taking the folders "Editor", "Plugins", and "Vuforia" as well as the files " readme_SDK.txt", "link.xml", and "license_4rdpartynotice.txt".  (Which is basically the files that's inside of an empty project, with the Vuforia files inside of it) - and replace them in your current project, as well as downgrading to 5.2.x.

I don't know if this is the only fix - but it made it work for me! Phew! 

having same problem. +1