Today while I was working with some CoreGraphics API’s, I encountered a error which I was seeing it for the first time. CG for dumping an error “CGGStackRestore: gstack underflow” in the console everytime I invoked a method that was doing some CG based operations. Googling around I found that in CoreGraphics, you can save (CGContextSaveGState) and restore (CGContextRestoreGState) the graphics state. When the  state is saved, a copy is put on the graphics state’s “stack”, and when it is restored, the top state on the stack is removed and used. If we restore the state more times than we save it and then when we try to remove and use the top item of the stack, the stack is empty, causing a stack “underflow” error. So just make sure you have enough save-restore state methods called and it will fix the issue.

CGGStackRestore