Subtract CGRect from CGRect — largest piece of one not containing the other

Question

How I can substract one CGRect from another? I want the result R1 - R2 to be the largest subrectangle of R1 that does not intersect R2.

Answer 1

Would probably go something like this:

CGRect frame = CGRectMake(0, 0, 320, 480);
float aWidth  = frame.size.width; /* say for instance 320 */
float aHeight = frame.size.height; /* say for instance 480 */

int final = aWidth - aHeight;
NSLog(@"Should be -160, your answer: %i",final);