You can enable iTunes File Sharing in two ways, both resulting in the same outcome: the UIFileSharingEnabled key will be set to YES.
Either open your app’s Info.plist file (by default it’s inside the Supporting Files folder in Xcode, as something like YourApp-Info.plist). Then hover over any of the items under Information Property List until you see a small plus icon and click it to add a row. Type UIFileSharingEnabled, then set the left box to YES.
The key will turn into Application supports iTunes file sharing:
Alternatively, head to your app’s target and select the Info category. Under Custom iOS Target Properties you’ll find the same list populated with human readable keys. Again hover over any of the cells until a plus icon appears, then click it to add a new row. Now use the drop down arrows to pick the option Application supports iTunes file sharing, and set its value to YES.
Now when you connect your device to iTunes you’ll be able to see your app in the file sharing option (under Your Device – Apps):
Note that your entire app’s Documents folder will be shared when you do this, including all folders you create in it. If you have data that you do not want your users to see you need to store them outside the Documents folder using software like Xender for PC, or start those file names with a “full stop” (such as .testfile). This will hide the file and hence it won’t show up in iTunes.