UIImagePickerController doesn't fill screen

Scaling by a fixed value isn't a good idea... as I'm sure anyone who used the accepted answer here probably found out when the iPhone 5 came out.

Here's a code snippet to scale dynamically based on the screen resolution to eliminate the letter boxing.

// Device's screen size (ignoring rotation intentionally):
CGSize screenSize = [[UIScreen mainScreen] bounds].size;

// iOS is going to calculate a size which constrains the 4:3 aspect ratio
// to the screen size. We're basically mimicking that here to determine
// what size the system will likely display the image at on screen.
// NOTE: screenSize.width may seem odd in this calculation - but, remember,
// the devices only take 4:3 images when they are oriented *sideways*.
float cameraAspectRatio = 4.0 / 3.0;
float imageWidth = floorf(screenSize.width * cameraAspectRatio);
float scale = ceilf((screenSize.height / imageWidth) * 10.0) / 10.0;

self.ipc.cameraViewTransform = CGAffineTransformMakeScale(scale, scale);

The camera's aspect ratio is 4:3 and the screen's aspect ratio is 3:2. So there is simply no way for the camera picture to fill the screen unless you're willing to crop is to 3:2. To do that, apply an appropriate scale transform.