according to apple's mac processor list a i5 should be a 64 bit processor. According to this video if i type uname -m in terminal i should get x86_64. but in my case it says i386 instead. why is that? i developed also an app, that is a 64 bit only app. that app is NOT running on this mac. it crashes at start. but if i compile in x86_64 mode instead of 64 bit only then it works. does somebody have an idea on how to fix this?
ARC is not supported under 32-bit runtimes. Therefore if you are using ARC you will need to produce 64-bit binaries only.
From Transitioning to ARC Release Notes:
ARC is supported in Xcode 4.2 for OS X v10.6 and v10.7 (64-bit applications) and for iOS 4 and iOS 5. Weak references are not supported in OS X v10.6 and iOS 4.