The deployment objective determines the ability of your application to run on older versions of iOS. When the new version of iOS comes out, some people do not bother to upgrade their devices to the latest version of iOS.
If you choose a higher deployment target (e.g. 12.1), your application will not be able to load for people who even have the latest devices, but an older version of iOS.
If you choose the lowest possible deployment target, some newer platforms may not work as expected, which increases the chances of the application crashing for older versions of iOS.
We use Deploymate for maximum back support. It warns of newer APIs and infrastructures and of obsolete methods, and then you start the fix for lower versions of iOS.
Tough guy
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