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#define kFPS 60

where do i exactly define the fps in the exported xcode project from unity.   (#define kFPS 60)  where is this?

Normally in AppController.mm

However its use is now deprecated

// kFPS define for removed

No, you need it in a script. Below is an example script that you could use - simply attach it to your ARCamera. This will also display the current FPS, though you will need to experiment a little. Please also try the Unity forums at the Unity web site to get up to speed with Unity a little more.

look like the script work just inside unity, but not when is on the iphone.