Unity 5 moved to ARC (Automatic Reference Counting). Starting from version 4.0.0, our Unity plugin supports ARC and doesn't require any additional steps
However, if you are using a version of our Unity plugin lower than 4.0.0, you will need to modify your Xcode project in order to properly build with our SDK. Simply go to "Build Phases" in your project settings and add the "-fno-objc-arc" flags to the following files under the Compile Sources section:
You can also add the flags directly from Unity, by right-clicking the files in the Unity inspector, and choosing "Compile flags".