How to specify arm6 when debugging in iphone4 device with Xcode 4?

Our product uses OpenCV as a library which is only support arm6. In Xcode 3.2, we can specify the active architecture to armv6 so that we can debug & test on iphone4 (which is actually armv7 cpu).

Today I upgraded my xcode to 4.0.2, and I found that when debugging on iphone4 , xcode will "smartly" recognize it and set the active architecture to armv7, which leads link error when debug in iphone4 device. If I force to set the valid architecture to armv6, it will gets compile error below:

No architectures to compile for (ONLY_ACTIVE_ARCH=YES, active arch=a开发者_如何转开发rmv6, VALID_ARCHS=armv6).

I want to know that, when debugging in iphone4 device, how to set the active architecture to armv6 in xcode 4?

Finally, I decide to upgrade my project to use armv7 opencv library. The bad effect is the iphone version of armv6 (which is iphone & iphone3G) is NOT supported any more.