Looming an image

We want an image show and hide many times, looming like fen-fire.

Declare an image above viewDidLoad.

let im = UIImage(named: "image")

Add these lines inside viewDidLoad.

UIGraphicsBeginImageContextWithOptions(im!.size, false, 0)

let empty = UIGraphicsGetImageFromCurrentImageContext()

UIGraphicsEndImageContext()

var te=[UIImage](count: 5, repeatedValue: im!)

        te.append(im!)

        te.append(empty)

        te.append(im!)

        te.append(empty)

        te.append(im!)

let iv = UIImageView(image:empty)

        iv.frame.origin = CGPointMake(100,50)

self.view.addSubview(iv)

        iv.animationImages = te

        iv.animationDuration = 2

        iv.animationRepeatCount = 100

        iv.startAnimating()

Run to see result, this effect can attract user attention when we show a warning. To change repeat times, edit animationRepeatCount.