At the moment I'm compiling for both armv6 and armv7. I've also set the target iOS version as 4.0.
Am I right in saying that all devices capable of running iOS 4.0+ are armv7, and thus I can stop compiling for armv6?
Not a big deal, but it means that my app's binary will be quite a bit smaller if I can.
Sorry, but you aren't right. The iPhone 3G and iPod Touch 2G are able to run iOS 4 (barely) and they include a armv6 processor.
ARMv8 / ARM64 = iPhone 5s, iPad Air, Retina iPad Mini ARMv7s = iPhone 5, iPhone 5c, iPad 4 ARMv7 = iPhone 3GS, iPhone 4, iPhone 4S, iPod 3G/4G/5G, iPad, iPad 2, iPad 3, iPad Mini ARMv6 = iPhone, iPhone 3G, iPod 1G/2G
iOS 4.3+ requires ARMv7. If your Deployment Target is 4.3, you can exclude armv6 support.
As of XCode 4.5 you cannot build for armv6 @Paul de Lange
You can safely drop armv6 support IF you set your deployment target to 4.3. This is because iOS 4 can be installed on armv6 devices only up to 4.2.
来源：https://stackoverflow.com/questions/6517822/do-i-need-to-add-armv6-support-when-limiting-apps-to-ios-4-0