Make blinking point

We want to make a small red blinking point to attract user attention.

Copy these lines in to viewDidLoad

var ar = [UIImage]()

        let w : CGFloat = 18

        for i in 0 ..< 6 {

            UIGraphicsBeginImageContextWithOptions(CGSizeMake(w,w), false, 0)

            let con = UIGraphicsGetCurrentContext()

            CGContextSetFillColorWithColor(con, UIColor.redColor().CGColor)

            let ii = CGFloat(i)

            CGContextAddEllipseInRect(con, CGRectMake(0+ii,0+ii,w-ii*2,w-ii*2))

            CGContextFillPath(con)

            let im = UIGraphicsGetImageFromCurrentImageContext()

            UIGraphicsEndImageContext()

            ar += [im]

        }

        let im = UIImage.animatedImageWithImages(ar, duration:0.5)

        button.setImage(im, forState:.Normal)

Blinking point will show nearby button.

If don’t want to see button, let set button background to white, so we see only red point.