Local storage it's perfect way to keep at hand all important files if you don't have iBridge Air around. Local Storage uses iPhone’s internal memory to store files and you will be able to access them without plugging in iBridge Air .
How to transfer files to Local storage?
You can access the local storage section by entering the “Manage Files” section and taping the middle icon in the bottom part of the screen.
You can move files to the local storage by selecting a file(s) you want to move, then tapping the three dots at the bottom right corner, then tapping “Move to..” line, then tapping local and selecting a desired folder in the local storage: