Question

I am trying to make a line graph using the drawRect method but I have came across a major problem. The 0 point on the iPhone screen is in the top left corner. Is there any way to either relocate the 0,0 point or change the coordinates input to where they would be if the 0,0 point was in the bottom left corner?

Heres My drawRect method

 - (void)drawRect:(CGRect)rect
{
CGContextRef context = UIGraphicsGetCurrentContext();

CGContextSetLineWidth(context, 1.0);

CGColorSpaceRef colorspace = CGColorSpaceCreateDeviceRGB();

CGFloat components[] = {0.0, 0.0, 1.0, 1.0};

CGColorRef color = CGColorCreate(colorspace, components);

CGContextSetStrokeColorWithColor(context,  [UIColor blackColor].CGColor);
//Coordinates of bottom left corner (480 went off screen)
CGContextMoveToPoint(context, 0, 460);
CGContextAddLineToPoint(context, 320, 0);


CGContextStrokePath(context);
CGColorSpaceRelease(colorspace);
CGColorRelease(color);
}

Answer 1

This page describes how to treat it as a right-hand coordinate system instead of a left-hand, which sounds like what you want