Have an old mac that can run snow leopard but can’t update to lion due to an incompatible processor?
Good news, save your cash.
It presumes your current XCode 4.2 installation is in /Developer, and make sure XCode is NOT running.
Download the Lion 4.3.1 XCode DMG file, and mount it so that you can see it from Finder.
Fire up a Terminal Window (Applications->Utilities->Terminal)
Now enter the following commands into the terminal (note, your password will have to be entered after the first command):
(Enter the commands one by one, don’t paste them all)
sudo cp -R /Volumes/Xcode/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS5.1.sdk /Developer/Platforms/iPhoneOS.platform/Developer/SDKs/
sudo cp -R /Volumes/Xcode/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator5.1.sdk /Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/
sudo cp -R /Volumes/Xcode/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/DeviceSupport/5.1\ \(9B176\) /Developer/Platforms/iPhoneOS.platform/DeviceSupport/
sudo rm -f /Developer/Platforms/iPhoneOS.platform/DeviceSupport/Latest
cd /Developer/Platforms/iPhoneOS.platform/DeviceSupport/
sudo ln -s ./5.1\ \(9B176\) ./Latest
After this is done, unmount xcode 4.3.1 from the finder then fire up xcode. You will now be able to build for ios5.1 under snow leopard.
I tested this myself as I have a iMac which runs Lion, but an old macbook which can’t.
Enjoy
Info sourced from : http://www.iphonedevsdk.com/forum/iphone-sdk-development/100229-snow-leopard-sdk-5-1-a.html [import]uid: 84637 topic_id: 23827 reply_id: 323827[/import]