with Xcode 8 libimobiledevice s could stop working. just in case if you see something like:
ERROR: Could not connect to lockdownd, error code -5
this should fix it (add your user to _usbmuxd group)
sudo dseditgroup -o edit -a $USER -t user _usbmuxd
ERROR: Could not connect to lockdownd, error code -5
this should fix it (add your user to _usbmuxd group)
sudo dseditgroup -o edit -a $USER -t user _usbmuxd