The Xcode 4.3 does not have a simulator other than 5.1 and 4.3, but sometimes we need to test apps on the lower environment. So here is the trick:
You need to have lower Xcode installation files, and copy the simulator folders to Xcode 4.3.
For exemple:
sudo mv /XCode file/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator4.1.sdk/ /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/
