Magnets and consumer electronics do not usually mix well, except for a few, well engineered cases. That tenuous relationship between the two seems to be the cause of some reported problems with the Optical Image Stabilization feature on their iPhone 6 Plus, as well as NFC performance on both the iPhone 6 and its larger sibling. And the source of this problem might be that fancy metallic case or magnetic accessory that you have may have just purchased from some reseller off the net.
Some, but not all, users have reported random problems with OIS and NFC functions of their iPhones, and it wasn’t clear at first what was to blame. By and by, it was speculated that these problems happened when the iPhone 6 or 6 Plus were equipped with accessories that happened to use metal or magnets, like some telephoto lens that attach to the phone’s metallic body.
Apple can hardly be blamed for such a limitation as the laws of physics must be upheld. If anything, perhaps the company can be faulted for burying that little known fact inside manuals, which barely anyone reads these days. And it hasn’t exactly fallen short of warning accessory makers about this peculiarity either, as those that are part of its MFi licensing program have been warned, or at least informed, of such problems. And some actually seem to be aware and do warn their users as well. Except sometimes buried inside manuals.
It might be a bigger problem when it comes to third-party accessory makers that aren’t part of Apple’s MFi club and are unaware of such warnings. This might be an opportunity for “sanctioned” accessory makers to preach about the benefits of their products. For now, aside from information dissemination, there is very little that can be done to address the issue from Apple’s side, so it simply best to avoid accessories that have magnets or even metal parts altogether.