Question

i’m researching on the time it will take and how to make a drawing pad for a elementary school kids. So it will be similar draw something, but only with the draw pad. Kids will be able to change different colors to draw it. So which frameworks should I look at? core graphics? Are there anything else? Can anyone point to a tutorial or directions? Thanks in advance.

Answer 1

Try this code ….

#pragma mark touches stuff...

    - (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
        UITouch *touch = [touches anyObject];
        lastTouch = [touch locationInView:imageView];

       }

    - (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
        UITouch *touch = [touches anyObject];
        currentTouch = [touch locationInView:imageView];

        CGColorRef strokeColor = [UIColor brownColor].CGColor;
        UIGraphicsBeginImageContext(imageView.frame.size);
        CGContextRef context = UIGraphicsGetCurrentContext();
        [imageView.image drawInRect:CGRectMake(0, 0, imageView.frame.size.width, imageView.frame.size.height)];
        CGContextSetLineCap(context, kCGLineCapRound);
        CGContextSetLineWidth(context,10); // 10 is the pen size

     CGContextSetStrokeColorWithColor(UIGraphicsGetCurrentContext(), [UIColor brownColor].CGColor); // this will be colour u need to change as required 
                CGContextSetBlendMode(context,kCGBlendModeDarken );



        CGContextBeginPath(context);
        CGContextMoveToPoint(context, lastTouch.x, lastTouch.y);
        CGContextAddLineToPoint(context, currentTouch.x, currentTouch.y);
        CGContextStrokePath(context);
        imageView.image = UIGraphicsGetImageFromCurrentImageContext();
        UIGraphicsEndImageContext();

        lastTouch = [touch locationInView:imageView];
    }

    - (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
    {
        UITouch *touch = [touches anyObject];
        lastTouch = [touch locationInView:imageView];
    }

I hope this will help you ….