title: Change the color of one pixel of an UIImage without creating a new UIImage/CGImage
body: <p>All solutions I've found for doing this (like this one <a href="https://stackoverflow.com/questions/31661023/change-color-of-certain-pixels-in-a-uiimage">Change color of certain pixels in a UIImage</a> ) suggest to create a new uiimage, but I want to modify directly a pixel in the uiimage without creating a new one. Is there a way to do this ?
  It seems that cgimage is not mutable, but is there a way to create an image from a pixel data buffer, and modifying this pixel data buffer would directly modify the image ?</p>