No, they can control what applications are allowed on their app store and control how the OS they distribute runs. Aside from those two things they can't really force anything that you haven't already allowed, or continue to operate.
Apple can't physically confiscate the phone or the data that you put onto it's hard drive (not talking about iCloud). It's yours. You can put linux on your iPhone if you want and there is nothing Apple can do about it.
Apple can't physically confiscate the phone or the data that you put onto it's hard drive (not talking about iCloud). It's yours. You can put linux on your iPhone if you want and there is nothing Apple can do about it.