title: swift: repeat animation after time
body: <p>I have this animation:</p>
  
  <pre><code>override func viewDidLoad() {
          super.viewDidLoad()
  _ = Timer.scheduledTimer(timeInterval: 15, target: self, selector: #selector(self.callingFunction), userInfo: nil, repeats: true)
  }
  
  @objc func callingFunction(){
          let image0:UIImage = UIImage(named: "next0.png")!
          let image1:UIImage = UIImage(named: "next1.png")!
          let image2:UIImage = UIImage(named: "next2.png")!
          let image3:UIImage = UIImage(named: "next3.png")!
          let image4:UIImage = UIImage(named: "next4.png")!
          let image5:UIImage = UIImage(named: "next5.png")!
          let image6:UIImage = UIImage(named: "next6.png")!
          let image7:UIImage = UIImage(named: "next7.png")!
  
          nextButton.setImage(image0, for: .normal)
          nextButton.imageView!.animationImages = [image0, image1, image2, image3, image4, image5, image6, image7]
          nextButton.imageView!.animationDuration = 1.0
          nextButton.imageView!.startAnimating()
      }
  </code></pre>
  
  <p>I need to repeat this animation in every 15 seconds. But this animation starts after 15 seconds and next execute every 1 second.  </p>