Why is my text flip over when using CGContextShowAtPoint?

Question

I am writing a simple practice. However, my text is flip upside down when I trying to use CGContext to put some string on the UIView, I am wondering why and how to change it into correct format.

Here is my code in the drawRect

    char *string = "TEST";
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextBeginPath(context);
CGContextSelectFont (context,"Helvetica-Bold",12, kCGEncodingMacRoman); 

CGContextShowTextAtPoint(context, 5, 5, string, strlen(string));

CGContextClosePath(context);

Thanx for your help.

Answer 1

CoreGraphics uses cartesian coordinates, so you need to translate your context before doing any drawing

CGContextRef context = UIGraphicsGetCurrentContext();

// transforming context
CGContextTranslateCTM(context, 0.0, rect.size.height);
CGContextScaleCTM(context, 1.0, -1.0);

// your drawing code