func setTableViewBackgroundGradient(sender: UITableViewController, _ topColor:UIColor, _ bottomColor:UIColor) {
let gradientBackgroundColors = [topColor.cgColor, bottomColor.cgColor]
let gradientLocations = [0.0,1.0]
let gradientLayer = CAGradientLayer()
gradientLayer.colors = gradientBackgroundColors
gradientLayer.locations = gradientLocations as [NSNumber]
gradientLayer.frame = sender.tableView.bounds
let backgroundView = UIView(frame: sender.tableView.bounds)
backgroundView.layer.insertSublayer(gradientLayer, at: 0)
sender.tableView.backgroundView = backgroundView
}