在为旧的SDK部署iOS应用程序时，如何进行测试?

I have written an app and its base SDK is set to 4.2, and at the moment it is in the app store with a deployment target set to 4.2, I'm sure you'll agree this is a bad idea because I am alienating all potential users who do not have the latest version of iOS installed.I have written an app and its base SDK is set t