Question

// This is the line which retrieves the current image on the UIView
CGImageRef originalImage = imageView.image.CGImage;

I declare this in a method I use to edit my image which can be called by several buttons.

Is there anyway I can declare this variable globally so it always holds the first image loaded in the UIView? I can then use a copy variable to do all the editing on e.g.

CGImageRef copyImage = originalImage;

I have tried to make it global by declaring it in the header file and instantiate it in the method file however when I try and access the global variable in another method it is as if it hasn’t been made global.

Any advice or better solutions would be greatly appreciated.

Answer 1

It is not entirely clear what you are trying to do, but what I would point out is:

1. the assignment

             CGImageRef copyImage = originalImage;
   

   will not create a copy of your image; it will simply give you a local variable pointing to the same image as originalImage; if you modify copyImage, you also modify originalImage;

2. if you want to make a copy of an CGImage so that you can modify it freely while keeping the original safe, use:

         CGImageRef img1 = CGImageCreateCopy(img2);
   

3. if you want to save your original image as under point 2, simply add a property to your class and initialize it soon after you have got your CGImage in place (e.g., in viewDidLoad:

          -(void) viewDidLoad {
              ...
              self.originalImage = CGImageCreateCopy(imageView.image.CGImage);
              ...
          }
   

self.originalImage will be your original image, while you will be able to freely modify imageView.image.CGImage.

Don’t forget to release the copied image in your dealloc method.

Hope this helps.