How do you draw to the view using Core Graphics on the iPhone

Question

I'm new to iPhone programming and can't figure out how to use Core Graphics. The code I am testing with is:

- (void)drawRect:(CGRect)rect{
CGContextRef ctx = UIGraphicsGetCurrentContext();
CGContextClearRect(ctx, rect);
CGContextSetRGBStrokeColor(ctx, 255, 255, 0, 1);
CGContextStrokeRect(ctx, CGRectMake(195, 195, 60, 60)); }

I put it in the ViewController.m file on a default View based application but nothing happens when the application is run.

Answer 1

drawRect is a method of the UIView class, not UIViewController . You need to create your own UIView subclass and implement that one's drawRect . To actually use the class, just set the class name in the xib file that comes with the view.

Answer 2

There are more resource available to learn Core Graphics , you just need to google..

See some good link to know more about Core Graphics and its uses.

Getting Started with Graphics & Animation

Core Graphics 101: Patterns