Backward-Compatibility-example.swift

import UIKit

class MyView: UIView {
  fileprivate var myPreviewInteraction: Any? = nil
  
  init() {
    super.init(frame: CGRect.zero)
    
    if #available(iOS 10.0, *) {
      myPreviewInteraction = UIPreviewInteraction(view: self)
      (myPreviewInteraction as! UIPreviewInteraction).delegate = self
    }
  }
  
  required init?(coder aDecoder: NSCoder) {
    fatalError("init(coder:) has not been implemented")
  }
}

@available(iOS 10.0, *)
extension MyView: UIPreviewInteractionDelegate {
  public func previewInteraction(_ previewInteraction: UIPreviewInteraction, didUpdatePreviewTransition transitionProgress: CGFloat, ended: Bool) { }
  public func previewInteractionDidCancel(_ previewInteraction: UIPreviewInteraction) { }
}