Is programmatically inverting the colors of an image possible?

Question

I want to take an image and invert the colors in iOS.

Answer 1

Tommy answer is THE answer but I'd like to point out that could be a really intense and time consuming task for bigger images. There two frameworks that could help you in manipulating images:

1. CoreImage
2. Accelerator
   
   And it really worth to mention the amazing GPUImage framework from Brad Larson, GPUImage makes the routines run on the GPU using custom fragment shader in OpenGlES 2.0 environment, with remarkable speed improvement. With CoreImge if a negative filter is available you can choose CPU or GPU, using Accelerator all routines run on CPU but using vector math image processing.