I am trying to enable ARC(Automatic Reference Count) functionality to my cocos2dbox2d application so i flow this link. ARC is enabled successfully and the application is working fine in iOS 6 but same application crash in ios 5.1. Crash report is
2012-12-01 13:33:07.753 SampleApp[6397:707] cocos2d: **** WARNING **** CC_ENABLE_GL_STATE_CACHE is disabled. To improve performance, enable it by editing ccConfig.h
2012-12-01 13:33:07.757 SampleApp[6397:707] cocos2d: cocos2d v2.0.0
2012-12-01 13:33:07.761 SampleApp[6397:707] cocos2d: Using Director Type:CCDirectorDisplayLink
dyld: lazy symbol binding failed: Symbol not found: _objc_setProperty_nonatomic
Referenced from: /var/mobile/Applications/03ACE817-3A67-456C-914A-90BC00B4AD38/SampleApp.app/SampleApp
Expected in: /usr/lib/libobjc.A.dylib
dyld: Symbol not found: _objc_setProperty_nonatomic
Referenced from: /var/mobile/Applications/03ACE817-3A67-456C-914A-90BC00B4AD38/SampleApp.app/SampleApp
Expected in: /usr/lib/libobjc.A.dylib
Check this image:

Any one help me…
Thanks…
If you are facing this error set your deployment target to 4.3. By default it is setting to 6(latest). Once we had all our projects and subprojects set to the same deployment target, the problem went away. If you want to enable ARC in your application you need to set deployment target as 5.0 and above.