UITableView contentOffset jumps after call to setContentOffset "programatically"

Hi guys,

I'll tell you my issue. After call to "setContentOffset" in my UITableView

self.tableView!.setContentOffset(CGPointMake(0, -227.5), animated: false)

when I begin a drag gesture over my UITableView the contentOffset is the same (0, -227.5) in delegate method "scrollViewWillEndDragging" but after in method "scrollViewDidScroll" the first contentOffset is very different, approximately (0, -152.5).

It shows a weird effect. The UITableView jumps sharply from point (0, -227.5) to (0, -152.5).

I attach a simple example code with the above problem:

class ViewController: UIViewController, UITableViewDataSource, UITableViewDelegate {
    @IBOutlet weak var tableView: UITableView!
  
    override func viewDidLoad() {
        super.viewDidLoad()
        /
      
        self.tableView!.contentInset = UIEdgeInsetsMake(82.5, 0, 0, 0)
    }
  
    override func viewDidAppear(animated: Bool) {
        super.viewDidAppear(animated)
      
        self.tableView!.setContentOffset(CGPointMake(0, -227.5), animated: true)
    }
    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        /
    }
  
    func numberOfSectionsInTableView(tableView: UITableView) -> Int {
        return 1
    }
  
    func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return 0
    }
  
    func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCellWithIdentifier("Cell", forIndexPath: indexPath)
      
        return cell
    }
}

Any help?

Regards.