If you got some weird errors from Reachability.m (my xcode is in version 4.6.3), something like the following:

Then just update your reachability files with the new ones.

Also, Select your project -> target -> Build Phases -> Compile Sources
-> Double click the Reachability.m -> add the flag -fno-objc-arc.

Ref: http://stackoverflow.com/questions/7877867/use-reachability-m-in-xcode-4-2