libobjc.A.dylib compile error on iOS 4.3

Question

I'm having a compiling error in iOS Simulator 4.3 I can't actually figure it out, The error I get is:

dyld: lazy symbol binding failed: Symbol not found: _objc_retain
  Referenced from: /Users/ben/Library/Application Support/iPhone Simulator/4.3.2/Applications/75915A97-7C3D-489A-B7B0-7B6895A4B584/AppName.app/AppName
  Expected in: /Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator4.3.sdk/usr/lib/libobjc.A.dylib

dyld: Symbol not found: _objc_retain
  Referenced from: /Users/ben/Library/Application Support/iPhone Simulator/4.3.2/Applications/75915A97-7C3D-489A-B7B0-7B6895A4B584/AppName.app/AppName
  Expected in: /Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator4.3.sdk/usr/lib/libobjc.A.dylib

Note:
The library being referenced (libobjc.A.dylib) is actually in the 'Expected Place' The code works fine on an iOS5 device, and in iOS5 Simulator.

Answer 1

Add -fobjc-arc in Build Settings => Other Linker Flags (OTHER_LDFLAGS) for the different configurations

Answer 2

This problem occurs if you use a library that uses ARC and want to build/run on older iOS 4 devices.

In Build Settings => Other Linker Flags

• Add -fobjc-arc
• If yet not solved, then add -weak_library /usr/lib/libobjc.A.dylib