Invert all alpha values of UIImage

I have a UIImage where some pixels have an alpha value of 0 and others have an alpha value of 1. I'm trying to figure out a way to invert all of the alpha values without inverting the actual RGB color channels.

I've been looking around for a solution but all I can find are examples of how to invert the RGB values that don't modify the alpha channel (so the opposite of what I'm looking for).