Drawing simple lines on iPhone with CoreGraphics

Question

I would like to draw a straight line between where a user touches the screen, and where the touch ends. i need multiple lines, for if the user repeats the touch-drag-release act

Answer 1

The Problem is that UIGraphicsGetCurrentContext() will return a null-reference. If you want to draw into an UIImage you can get the CGContextRef as follows:

UIGraphicsBeginImageContext(anUIImage);

now calling UIGraphicsGetCurrentContext() will not longer return a null-reference.

... drawing goes here

UIImage* drawnImage = UIGraphicsGetImageFromCurrentImageContext();
// display the image on an view
UIGraphicsEndImageContext();