UIRefreshcontrol - UItableview header 视图被卡住并且没有显示 refreshview

UIRefreshcontrol - UItableview header view is stuck and refreshview is not showing

我在 UITableView 上添加了一个 UIRefreshControl。第一次加载屏幕时它工作正常。从第二次开始,每当我在 viewWillAppear 中调用 beginRefreshing 时,table 视图 header 就会卡住,刷新控件也不会显示。

可能是什么问题?

    override func ViewDidLoad(){

    refreshControl.addTarget(self, action: #selector(PlacesViewController.pullToRefresh), forControlEvents: .ValueChanged)
    tableView.addSubview(refreshControl)
    tableView.tableFooterView = UIView()
    self.tableView.contentInset = UIEdgeInsets(top: 0, left: 0, bottom: 110, right: 0)

        FetchExtPlaceList([:],inBackground:inBackground)

}

func FetchExtPlaceList(pramrDisc:parameter,inBackground:Bool){

    if !inBackground{
        ActivityManager.ManageActivityView(self, action: .ActionAdd)
    }else if pageNumber == 1 {
        self.refreshControl.beginRefreshing()

    }


    WSRequest.SendRequest(WSMethod.POST, pramrDisc: pramrDisc, paramsString: nil, operation: WSOperation.FetchExtPlaceList, completionHandler: { response in

        if !inBackground{
            ActivityManager.ManageActivityView(self, action: .ActionRemove)
        }

        if let errorTitle = response.errorTitle {

            if let errorDescription = response.errorDescription {
                UIAlertController.ShowAlert(errorTitle, message: errorDescription)
            }

        }else if let wsError = response.wsError {

            if let infoMessage = wsError.infoMessage {
                UIAlertController.ShowAlert("", message: infoMessage)
            }else if let errorMessage = wsError.errorMessage {
                UIAlertController.ShowAlert("", message: errorMessage)
            }else if let error = wsError.error {
                UIAlertController.ShowAlert("", message: error.description)
            }

        }else{

            if let places = response.parsedObject as? [Place]{

                if self.pageNumber == 1 {
                    self.places.removeAll()
                }

                self.places.appendContentsOf(places)
                self.tableView.reloadData()
            }

        }

        if self.refreshControl.refreshing{
            self.refreshControl.endRefreshing()
        }
    })
}

我知道了。我以编程方式调用尝试开始刷新,但我在 Here 上发现我必须通过更改 contentoffset 来滚动 table 视图。