Pink Lines on front facing camera

Does this work when you are using the native Camera app on the iPhone instead of an app? If it works well under the native app, I would delete the app on the iPhone and then download and install it again. If it still does not work correctly, then it is probably the camera, so under those circumstances, you need to use the Get Support link at the top of the page here to contact Apple Support, or if you have an Apple Store close by, you can make a Genius Bar appointment to have the device examined by Apple and they will explain your options. Genius Bar Reservation and Apple Support Options - Apple

There is a problem with the camera then if you are seeing this and have to take an alternative action to correct it. Seeing these pink lines and having to switch cameras back and forth is not normal behavior and indicates a problem.