Can I edit the pixels of the UIImage's property CGImage

Question

UIImage has a read-only property CGImage. I have to read its pixels to a memory block and edit them and then make a new UIImage to replace the old one. I want to know if th

Answer 1

The short answer is no. However, you say you have to make a copy anyhow, so why not just get an NSData object and manipulate its bytes.

From the Apple docs on UIImage:

Because image objects are immutable, they also do not provide direct access to their underlying image data. However, you can get an NSData object containing either a PNG or JPEG representation of the image data using the UIImagePNGRepresentation and UIImageJPEGRepresentation functions.

To get the data as a PNG, use:

NSData * UIImagePNGRepresentation (
   UIImage *image
);

for JPEG, use:

NSData * UIImageJPEGRepresentation (
   UIImage *image,
   CGFloat compressionQuality
);