CAShapeLayer *circle = [CAShapeLayer layer];
[circle setPath:[[UIBezierPath bezierPathWithOvalInRect:CGRectMake(100, 100, 150, 150)] CGPath]];
[circle setStrokeColor:[[UIColor blueColor] CGColor]];
[circle setFillColor:[[UIColor clearColor] CGColor]];
[[self.view layer] addSublayer:circle];