Adding the wave’s animatableData property

We now have a wave shape that we can duplicate as many times as needed to create a layered ocean scene. However, those waves are still static, meaning they won’t do anything unless we have a way of changing the value in the yOffset variable. To accomplish that, we need to add one more important variable to the file here: animatableData.

So, let’s add it right under the declaration of the yOffset variable:

var animatableData: CGFloat {
        get {
            return yOffset
        }
        set {
            yOffset = newValue
        }
    }

The animatableData property is an instance of a Swift class called Animatable...