iOS：如何在白色背景上应用自定义图像滤镜

Question

I want to do something like this:

Take an image with white background, and apply black colour only in the rest of the image.

How can I do this with iOS?

Answer 1

I have done something similar to create bar button images. Toy create a context, paint it white, turn your images into "masks" using Quartz functions, then draw them into the context. If this works for you leave a comment below I'll track down my link.