Arc / Circle animation in iphone

Question

How would I animate a circle on the iPhone so that the arc starts at \"0 degrees\" and ends at \"360 degrees\"?

Advance Thanks, Sat

Answer 1

you should read the documentation that Felixyz provided and if you want an example of how to animate the circle have a look over the MBProgressHUD at this link link text. The loader has two modes one with a UIViewActivityIndicator and a progress indicator (a filling circle that it is animated from 0 to 360 degress) i think the last mode is what you want.

the fallowing code is from copy/paste from that implementation that animates the circle:

- (void)drawRect:(CGRect)rect {
    CGRect allRect = self.bounds;
    CGRect circleRect = CGRectMake(allRect.origin.x + 2, allRect.origin.y + 2, 
                                   allRect.size.width - 4, allRect.size.height - 4);
    CGContextRef context = UIGraphicsGetCurrentContext();
    // Draw background
    CGContextSetRGBStrokeColor(context, 1.0, 1.0, 1.0, 1.0); // white
    CGContextSetRGBFillColor(context, 1.0, 1.0, 1.0, 0.1); // translucent white
    CGContextSetLineWidth(context, 2.0);
    CGContextFillEllipseInRect(context, circleRect);
    CGContextStrokeEllipseInRect(context, circleRect);
    // Draw progress
    float x = (allRect.size.width / 2);
    float y = (allRect.size.height / 2);
    CGContextSetRGBFillColor(context, 1.0, 1.0, 1.0, 1.0); // white
    CGContextMoveToPoint(context, x, y);
    CGContextAddArc(context, x, y, (allRect.size.width - 4) / 2, -(PI / 2), 
                                   (self.progress * 2 * PI) - PI / 2, 0);
    CGContextClosePath(context);    CGContextFillPath(context);
}

but read the documentation first! hope it helps