iPhone's front camera has a purple tint

This could be a number of things, one of which could be as MrBill3 stated a filter. Another thing it could be is a problem within the phone itself, damages such as water damage or even breaking the screen could have caused the camera to break. I would recommend visiting a local Apple Authorized Repair center to have them take a look at it.

Hello,

Check to see if you have a "filter" turned on. See this:

Take and edit photos with your iPhone, iPad, and iPod touch

Good luck.