When the Intel-based Macintosh computers were first revealed, it was shown that creating a program to be able to run on both Intel and PowerPC processors could be as simple as clicking a button. The keyword here being could. If you are starting up a new project, geared for only Mac OS 10.4, then this might be a fairly straightforward process. Otherwise, it might take a little extra work to get a Universal Binary working properly.

In the efforts to convert some older Edenwaith projects like Untar and Permanent Eraser to Universal Binaries, yet still remain backwards compatible with pre-Panther systems, I had to jump through several extra hoops.

Get the latest tools

Get the latest version of Xcode. At the time of this writing, the most recent version of Xcode was 2.3.

Upgrade To Native Target

If you have an older project, especially one which was originally generated with Project Builder (the precursor to Xcode), then you will need to first upgrade your application to a native application. This was the most important step that was often not mentioned before being able to compile your application as a Universal Binary.

Select your project in the Groups & Files window, and then go to Project → Upgrade To Native Target menu. If you have multiple targets you'd like to upgrade, then select the Upgrade All Targets In Project To Native.

Set Build Target Settings

Cross-Develop Using Target SDK: <Multiple values >
Architectures: ppc i386
Turn off Prebinding and Zerolink.

Setting Compiler Variables

GCC_VERSION_i386	4.0
GCC_VERSION_ppc	3.3
MACOSX_DEPLOYMENT_TARGET_i386	10.4
MACOSX_DEPLOYMENT_TARGET_ppc	10.2
OTHER_LDFLAGS_ppc	-prebind
SDKROOT_i386	/Developer/SDKs/MacOSX10.4u.sdk
SDKROOT_ppc	/Developer/SDKs/MacOSX10.2.8.sdk

Troubleshooting

If Zerolink isn't turned off, this error might appear:
can't locate framework for: -framework ZeroLink
Command /usr/bin/gcc-3.3 failed with exit code 1

If you are compiling in Deployment mode, this should avoid some of these headaches since ZeroLink isn't turned on by default, only with Development.

• Cross-Development Programming Guide
• Universal, 10.3 and up Applescript Studio application
• Universal Binaries and Jaguar
• Universal builds for PPC & x86