How to choose arch for osx project

I found that default template Cocoa project containts i386 arch in build settings. But in general I develops for osx 10.6+(10.开发者_如何学运维7). Is i386 required option or not?

Any Mac that can run 10.7 can run a 64-bit app. If your app is 64-bit only, then some Macs built before 2007, with a Core 1 processor, won’t be able to run it. If i386 support is easy, there’s no reason to turn it off, and it will be easier if you support it from day 1. But any Mac built in the last four years should support 64-bit.