drawing line in button event handler in objective c IOS 5

Question

i tried to draw line in objective c using this function

-(IBAction) DrawLine
{
    CGContextRef c = UIGraphicsGetCurrentContext();

        CGFloat red[4] = {1.0f, 0.0f, 0.0f, 1.0f};
        CGContextSetStrokeColor(c, red);
        CGContextBeginPath(c);
        CGContextMoveToPoint(c, 5.0f, 5.0f);
        CGContextAddLineToPoint(c, 50.0f, 50.0f);
        CGContextStrokePath(c);
}

but i found that c is null or nil why ? and what is the solution ?

Answer 1

I found The answer in

http://www.techotopia.com/index.php/An_iOS_5_iPhone_Graphics_Drawing_Tutorial_using_Quartz_2D