Xcode: Architectures settings for a universal\iOS4 app

I was wondering what my project settings should be in case I have a universal app that I am now updating to 4.0.

The Base SDK is iPhone Device 4.0 iPhone OS Deployment Target is iPhone OS 3.0

What should I enter in the Architectures, Build Active Architecture Only checkbox and the Valis Architectures for the different configu开发者_如何学Gorations (debug, release)?

Also, since some of my apps are not universal but will support 4.0 as base and 3.0 as deployment, will it make any difference is the architectures settings?

Thanks

Roi

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Base SDK should be set to the most recent version of the SDK (ie: 4.2) this is what you build against and ensures that your app works properly on new OS's. Xcode now has a 'Latest iOS' selection which I recommend.

Deployment Target is the minimum version you want your app to be able to be installed on. This is mostly dictated by the features you want to use. If you want features introduced in iOS 4, you need to set the deployment target to 4.0.

also, be careful that these are set identically for all configurations and don't vary between development and release.