Long story short, you can now import photos from your camera to an iPhone using a Lightning to USB Camera Adapter available from Apple.
Apple has rolled out in the past the functionality to import photos directly from your camera onto an iPad, but in this latest iOS 9.2 release the update seems to make importing photos to both the iPad and now iPhone more reliable than it was in the past.
We’re excited that Apple is slowly working towards making wired tethering from a camera to an iPad or iPhone a possibility, and this new feature does, to a certain extent, introduce the ability to tether with a cable from a camera directly into an iPad or iPhone.
The process is still somewhat clunky and limited, as the imported photos show up on the iPad or iPhone as a thumbnail, and the only way to view the image full screen to is to click over to Photos from the Import Screen.
We tried shooting photos while tethered and found that the Photos app worked fine with an older Nikon camera that utilized USB 2.0 cables, but crashed using our Nikon D800 which uses USB 3.0 cables. Your tests may vary.
We’re hopeful that this new added support in iOS 9.2 for iPhones will allow developers to create in-depth tethering apps in the future, but there’s currently no word that Apple has opened up the developer API to work on creating solutions for full capability tethering apps. 
