You need to have a jailbroken device.
1 install OpenSSH and set up Cyberduck on your computer.
2 Navigate to “/System/Library/Fonts/Cache/”.
3 Replace Helvetica.ttf and HelveticaBold.ttf with your chosen fonts.If you don’t know how to use Cyberduck with your iPhone, read this:
1 Make sure you are connected to Wi-Fi
2 Open Cydia on your iPhone, search for OpenSSH, and install it.
3 Download Cyberduck
to your computer. Open it and click on Bonjour. You should see your iPhone’s name in the Bonjour list.
4 Double click on your iPhone’s name. Cyberduck will attempt to connect to your iPhone, so your iPhone needs to be turned on for the whole time. I just set my auto-lock to Never so I don’t have to “slide to unlock” a bunch of times. The first time Cyberduck connects to your iPhone will take 30-50 secs, but subsequent connections should be instantaneous. If it times out or errors, just try again.
5 When you get to the login screen, enter the username root and the password alpine. Congratulations! You have access to your iPhone’s filesystem!
6 Click on the dropdown that says, “/private/var/root” and select “/”. You are now in the root folder and are ready to do any hacking that requires modification of system files!