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];