Swift：UIRefreshControl在向下拖动时不会通过

Question

我有一个工作的UITableView，我在其中添加了一个UIRefreshControl：

//load friends
func loadFriends() {
    globalClass.requestsIn = []
    globalClass.requestsOut = []
    globalClass.finalSections = []
    globalClass.myFriends = []
    finalSections = []
    sectionsG1 = []

    let queryIn1 = PFQuery(className:"Friendship")
    queryIn1.whereKey("toUser", equalTo: PFUser.currentUser()!.username!)
    let queryOut = PFQuery(className:"Friendship")
    queryOut.whereKey("fromUser", equalTo: PFUser.currentUser()!.username!)

    let query = PFQuery.orQueryWithSubqueries([queryIn1, queryOut])
    query.orderByDescending("createdAt")
    query.findObjectsInBackgroundWithBlock {
        (objects: [AnyObject]?, error: NSError?) -> Void in
        if error == nil {

            if objects!.count == 0 {
                self.friendtTableView.reloadData()
                self.text()
            } else {
                for object in objects! {
                    let toUser:String = object["toUser"] as! String
                    let status:String = object["status"] as! String
                    if toUser == PFUser.currentUser()?.username {
                        if status == "pending" {
                            globalClass.requestsIn.append(object["fromUser"] as! String)
                            self.update()
                        } else if status == "approved" {
                            globalClass.myFriends.append(object["fromUser"] as! String)
                            globalClass.myFriends = globalClass.myFriends.sorted { $0.localizedCaseInsensitiveCompare($1) == NSComparisonResult.OrderedAscending }
                            self.update()
                        }
                    } else {  if status == "pending" || status == "rejected" {
                        globalClass.requestsOut.append(object["toUser"] as! String)
                        self.update()
                    } else if status == "approved" {
                        globalClass.myFriends.append(object["toUser"] as! String)
                        globalClass.myFriends = globalClass.myFriends.sorted { $0.localizedCaseInsensitiveCompare($1) == NSComparisonResult.OrderedAscending }
                        self.update()
                        }
                    }
                }
            }

            if self.tableSegment == 1 {
                if globalClass.requestsIn.count == 0 {
                    self.friendTableView.reloadData()
                    self.text()
                } else {
                }
            } else if self.tableSegment == 2 {
                if globalClass.requestsOut.count == 0 {
                    self.friendTableView.reloadData()
                    self.text()
                } else {
                }
            } else if self.tableSegment == 0 {
                if globalClass.myFriends.count == 0 {
                    self.friendTableView.reloadData()
                    self.text()
                } else {
                }
            }
            self.refresher.endRefreshing()
        } else {
        }
    }
}

这适用于其他UITableViews，但由于某种原因不适用于此。当拖动停止时，旋转器永远不会旋转，只是捕捉到顶部。什么可能导致这种情况？

编辑：loadFriends功能

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