ios - Swift Firebase UIRefreshControl

Question

我正在尝试重新加载我的表格 View ，以便用户可以获得与其位置相关的刷新数据。我当前的设置是这样的，当我执行“拉动刷新”时，它将开始向 TableView 添加重复数据，而不是清除它并用新数据替换它。我觉得有 1 行代码可以解决这个问题，但我不知道它是什么，我觉得我以前在某个地方见过它......

var refresher: UIRefreshControl!

override func viewDidLoad() {
    super.viewDidLoad()


    searchController.searchResultsUpdater = self
    searchController.dimsBackgroundDuringPresentation = false
    definesPresentationContext = true
    tableView.tableHeaderView = searchController.searchBar

    locationManager.delegate = self
    locationManager.distanceFilter = kCLLocationAccuracyNearestTenMeters
    locationManager.desiredAccuracy = kCLLocationAccuracyBest
    locationManager.startUpdatingLocation()
    locationManager.stopUpdatingLocation()

    getTableViewData()

    refresher = UIRefreshControl()
    refresher.attributedTitle = NSAttributedString(string: "Pull to refresh")
    refresher.addTarget(self, action: #selector(RegisteredLocationsTableView.handleRefresh(refreshControl:)), for: UIControlEvents.valueChanged)
    tableView.addSubview(refresher)
}

func handleRefresh(refreshControl: UIRefreshControl) {
    getTableViewData()

    self.tableView.reloadData()
    refreshControl.endRefreshing()
}

func getTableViewData() {
    databaseRef.child("Businesses").queryOrdered(byChild: "businessName").observe(.childAdded, with: { (snapshot) in

        let key = snapshot.key

        if(key == self.loggedInUser?.uid) {
            print("Same as logged in user, so don't show!")
        } else {
            if let locationValue = snapshot.value as? [String: AnyObject] {
                let lat = Double(locationValue["businessLatitude"] as! String)
                let long = Double(locationValue["businessLongitude"] as! String)
                let businessLocation = CLLocation(latitude: lat!, longitude: long!)

                let latitude = self.locationManager.location?.coordinate.latitude
                let longitude = self.locationManager.location?.coordinate.longitude
                let userLocation = CLLocation(latitude: latitude!, longitude: longitude!)

                let distanceInMeters : Double = userLocation.distance(from: businessLocation)
                let distanceInMiles : Double = ((distanceInMeters.description as String).doubleValue * 0.00062137)
                let distanceLabelText = "\(distanceInMiles.string(2)) miles away"

                var singleChildDictionary = locationValue
                singleChildDictionary["distanceLabelText"] = distanceLabelText as AnyObject
                singleChildDictionary["distanceInMiles"] = distanceInMiles as AnyObject
                self.usersArray.append(singleChildDictionary as NSDictionary)
                self.usersArray = self.usersArray.sorted {
                    !($0?["distanceInMiles"] as! Double > $1?["distanceInMiles"] as! Double)
                }
            }
            //insert the rows
            //self.followUsersTableView.insertRows(at: [IndexPath(row:self.usersArray.count-1,section:0)], with: UITableViewRowAnimation.automatic)
            self.followUsersTableView.reloadData()
        }

    }) { (error) in
        print(error.localizedDescription)
    }

}

Answer 1

在方法getTableViewData内尝试执行usersArray.removeAll()。

此外，我建议不要在 handleRefresh 方法中执行这些操作:

self.tableView.reloadData()
refreshControl.endRefreshing()

原因:因为您需要在使用 getTableViewData() 方法获取数据后执行此操作。实际上，您已经在 getTableViewData() 方法的末尾进行了重新加载。因此，只需在 refreshControl.endRefreshing() 中调用它即可。但您可能会问，此刷新控件无法从此方法访问，这意味着您需要将其设置为全局属性。

如果您需要帮助，请在评论中告诉我。