You can use your iPhone/iPad to print to a printer when you have no Wifi network available. An example of this would be if you are in a truck or if you are visiting hotel.
Follow the steps below to enable mobile printing.

1. Enable the "Personal Hotspot" in the device Settings app
2. Connect your WiFi printer to the Personal Hotspot via WiFi (consult your printer instructions to see how to do this for your printer model)
3. Open Print n Share, choose something to print and tap on Print in the top right to show the Print screen. Then tap on "Choose" to find your WiFi printer and then tap print.

For Brother mobile printers, tap on Setup in the Print screen to show the setup screen. If the "Brother Mobile" test is not showing, tap on "More" to add it. Tap on "Test" beside "Brother Mobile" to test the connection. Once the connection is confirmed, then the 'Brother Mobile' option should be selected in the bottom of the screen for Documents and Text.

Note: You will need the "Personal Hotspot" function enabled on your iPhone to use this method, your carrier may have restrictions for this so check with them for further details.