I got an image I want to mask on the fly. The mask is basically shaped like a part-circle and changes in volume from time to time. Therefor I need to create an in-memory image, draw the mask circle stuff to it and do the masking on the original image like described in How to Mask an UIImageView.
The thing is that I got no idea how to create an in-memory image I may use for masking and I can apply basic drawing opperations on.t