While Apple has kept both iOS and OS X separate, over the years both platforms have started to gain features and functions that would allow them to communicate with each other wirelessly, such as the Continuity feature and Handoff, not to mention iCloud also helps to sync data across both platforms including contact data and photos.
However in a recently discovered patent from Apple, it shows that the Cupertino company is thinking about how your iOS device could potentially be used as an input tool of sorts for certain softwares running on the desktop. For example apps such as Final Cut Pro could allow additional functionality on your iOS device such as rewinding/fast forwarding through footage, or where apps like Photoshop could allow the screen of your iOS device to act like a drawing tablet using your finger.
To be fair, Photoshop does have a similar feature but the patent talks about making it more functional and taking it even further. It should be noted that the patent was filed way back in 2010 which means that Apple has been sitting on the idea for a while now. There’s no telling if the company plans on making it a reality but with Apple planning the launch of a 12-inch iPad, perhaps this is where such a feature could come in handy.