Animate Background Image continously in a loop using Swift, UIKit

I want to animate the following background image, when it reaches down it should go up again. I want to animate only one image. Somehow the image is not visible when I run the code. The image dimensions are as follows width: 375 and height: 666

Here is the image

Here is the code

import UIKit

class ViewController: UIViewController {

@IBOutlet weak var myView: UIView!
var water:UIImageView!

var hover:CABasicAnimation!
override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.
    water = UIImageView(image: UIImage(named: "water"))
    water.frame = CGRect(x: 0, y: 0, width: 375.0, height: 666.0)

    water.contentMode = .scaleAspectFill

    UIView.animate(withDuration: 4.0, delay: 0, options: UIViewAnimationOptions.curveLinear, animations: {
        self.water.frame.origin.y = self.view.bounds.height + self.water.frame.height - 50

    }, completion: nil)

    self.view.insertSubview(water, aboveSubview: myView)





}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}

}

You can use [.repeat, .autoreverse] options in your animation

UIView.animate(withDuration: 4.0, delay: 0, options: [.repeat, .autoreverse, .curveLinear], animations: {
    self.water.frame.origin.y = self.view.bounds.height + self.water.frame.height - 50

}, completion: nil)

Hope it help. :)