The application, originally filed by Apple with the US Patent and Trademark Office in late 2010, involves a "back panel for a portable electronic device with different camera lens options".
Apple's smartphone currently does not allow users to switch the lens or optics for the camera.
But the patent filing, reported by Apple Insider, outlines a system that would unlock swappable optics on the device, potentially ushering in official attachments such as a fisheye or close-up.
Instead of a fixed backplate as in current iOS devices, the proposed solution would involve a special removable rear casing that would give access to the camera optics.
In summary, the patent filing says: "A portable electronic device includes a digital imaging subsystem with a lens having an optical axis. A case encloses and supports the digital imaging subsystem in a first defined positional relationship to the case.
"A removable panel is coupled to the case and held in a second defined positional relationship to the case that covers the digital imaging subsystem without the removable panel being directly connected to the digital imaging subsystem.
"An optical component is supported by the removable panel such that the optical component is aligned with the optical axis and alters optical characteristics of the digital imaging subsystem."
It adds: "The device may include a power supply and an electronic control system coupled to the digital imaging subsystem and the power supply enclosed in and supported by the case. Electrical connectors may couple the power supply and the electronic control system to an electrical component on the removable panel."
The system could allow Apple to launch official, specialist lenses for the iPhone, such as fisheye, wideangle, close-up and macro lens.
Apple Insider feels that it could also enable photographers to place IR filters on the backplate to take, for example, black and white images.
Various companies already offer third-party accessories to change the camera in iOS devices, but a built-in system could offer greater functionality and usability.
The patent filing is no guarantee that the technology is actually in the works at Apple, but the firm's co-founder Steve Jobs told his biographer Walter Isaacson before he passed away last year that photography was among the technologies that he wanted to reinvent.