Question

so I’m doing this painting application in iOS, and I have a question…

Right now I draw a circle where the user taps… But here’s the problem. When the user taps again, the first circle is moved to the new place. What I want to do is draw a new circle at that position, not move the old one.

I’m using some standard code that is being used in many examples around the net…

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch *theTouch = [touches anyObject];

startPoint = [theTouch locationInView:self];  

startPoint.x -= 20;
startPoint.y -= 20;

[self setNeedsDisplay];
}

- (void)drawRect:(CGRect)rect
{
// Drawing code

CGContextRef context = UIGraphicsGetCurrentContext();

CGContextSetLineWidth(context, 2.0);

CGContextSetStrokeColorWithColor(context, [UIColor blueColor].CGColor);

CGRect rectangle = CGRectMake(startPoint.x,startPoint.y,25,25);

CGContextAddEllipseInRect(context, rectangle);

CGContextFillEllipseInRect(context, rectangle);

CGContextStrokePath(context);

}

I know this is probably a pretty noob-ish question 🙂
Also, if anyone could point in the direction of a tutorial or something explaining how to save my image afterwards, that would be really helpful as well…

Answer 1

You will need to track the history of all tap locations and draw a circle at each of those locations in your drawRect method.

For saving as an image you will need to draw to a bitmap context, have a look at Apple’s Quartz 2D Programing Guide for examples of how to do it.