devs, as mentioned by Erica IOKit is a semi private framework; does anybody has any experience in using it in an app-store app? I want to use it to get IMEI and ICCID number.
Yes, it will. IOKit is not a public framework on iOS.
If you call any non-documented Apple framework your app will be rejected. So it's very unlikely people have experience of using this framework in an app-store friendly app.
This process is entirely automatic, and happens immediately after you submit the binary. It's run through a number of checks to make sure you're not referencing or calling anything untoward.