How can i check the compatibility of my application, based on IOS 5.0.1 created with Xcode 4.3.3 on Lion, on IOS 6 without having to change my current MAC OS version and Xcode? Is there any way? And as an addition to this question, if i submit my application to the Apple Store, can it be rejected just for the simple reason of being created compatible with IOS 5 and not with IOS 6.
It’s not clear what you mean by “compatible”. One thing is the version of the SDK you link against, one thing is your Deployment Target setting and then there’s actual code compatibility regarding various API, UI and behaviour differences between iOS 5 and 6.
It seems that you have to develop with at least the iOS 6 SDK to submit your app at all.
However, your Deployment Target setting may go as low as required, so that your app still supports older iOS versions.
Your app doesn’t have to be “compatible” with iOS 6 in the sense that you tested it on iOS 6 and handled all the potential quirks that may have appeared by moving from iOS 5 to iOS 6. Of course, the user experience on iOS 6 could suffer in this case, but unless there’s a major bug, the reviewer doesn’t care.