Swift Firebase UIRefreshControl 创建重复的帖子
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【中文标题】Swift Firebase UIRefreshControl 创建重复的帖子【英文标题】：Swift Firebase UIRefreshControl creates duplicate posts 【发布时间】：2018-02-09 16:03:08 【问题描述】：当我在这个视图控制器上为我的 tableview 数组使用 UIRefreshControl 时，它只会添加两个重复的帖子，使其成为 3 个相同的帖子，而不是只显示已经存在的 1 个。我在不同的视图控制器上有一个 UIRefreshController 并且它们工作正常，但我认为这与我的 firebase 调用有关，因为我正在检查loggedInUser 以及他们关注的人并将这些帖子添加到数组中。不知道如何将我的呼叫切换到它只是刷新而不是复制的位置。谢谢。
override func viewDidLoad()
super.viewDidLoad()
databaseRef = Database.database().reference()
locationManager.delegate = self
locationManager.distanceFilter = kCLLocationAccuracyNearestTenMeters
locationManager.desiredAccuracy = kCLLocationAccuracyBest
locationManager.startUpdatingLocation()
locationManager.stopUpdatingLocation()
// refresh control
let refreshControl = UIRefreshControl()
refreshControl.addTarget(self, action: #selector(refreshControlAction(refreshControl:)), for: UIControlEvents.valueChanged)
self.feedTableView.insertSubview(refreshControl, at: 0)
override func viewWillAppear(_ animated: Bool)
super.viewWillAppear(animated)
if CLLocationManager.locationServicesEnabled()
switch(CLLocationManager.authorizationStatus())
case .notDetermined, .restricted, .denied:
print("No access")
fetchPosts(refreshing: false, refreshControl: nil)
//getAllPostsWithoutLocation(refreshing: false, refreshControl: nil)
case .authorizedAlways, .authorizedWhenInUse:
print("Access")
fetchPostsWithLocation(refreshing: false, refreshControl: nil)
//getAllPosts(refreshing: false, refreshControl: nil)
else
print("Location services are not enabled")
@objc func refreshControlAction(refreshControl: UIRefreshControl)
if CLLocationManager.locationServicesEnabled()
switch(CLLocationManager.authorizationStatus())
case .notDetermined, .restricted, .denied:
print("No access")
fetchPosts(refreshing: true, refreshControl: refreshControl)
//getAllPostsWithoutLocation(refreshing: true, refreshControl: refreshControl)
case .authorizedAlways, .authorizedWhenInUse:
print("Access")
fetchPostsWithLocation(refreshing: true, refreshControl: refreshControl)
//getAllPosts(refreshing: true, refreshControl: refreshControl)
else
print("Location services are not enabled")
func fetchPostsWithLocation(refreshing: Bool, refreshControl: UIRefreshControl?)
Database.database().reference().child("user_profiles").child((loggedInUser?.uid)!).child("following").observe(.value, with: snapshot in
if snapshot.exists()
MBProgressHUD.showAdded(to: self.view, animated: true)
let databaseRef = Database.database().reference()
// retrieves all users from database
databaseRef.child("user_profiles").queryOrderedByKey().observeSingleEvent(of: .value, with: (usersSnapshot) in
let users = usersSnapshot.value as! [String: AnyObject]
// retrieve user's following list and append it
for (_, value) in users
print(value)
if let userID = value["uid"] as? String
if userID == Auth.auth().currentUser?.uid
print(value)
if let followingUsers = value["following"] as? [String : String]
for (_,user) in followingUsers
self.following.append(user)
// append user's id to see own posts
//self.following.append(Auth.auth().currentUser!.uid)
// retrieve all posts from the database
databaseRef.child("posts").queryOrderedByKey().observeSingleEvent(of: .value, with: (postsSnapshot) in
let posts = postsSnapshot.value as! [String: AnyObject]
// retrieve posts of each follower and user
for (_, post) in posts
for (_, postInfo) in post as! [String: AnyObject]
if let followingID = postInfo["uid"] as? String
for each in self.following
if each == followingID
guard let uid = postInfo["uid"] as! String! else return
guard let caption = postInfo["caption"] as! String! else return
guard let downloadURL = postInfo["download_url"] as! String! else return
guard let name = postInfo["businessName"] as! String! else return
guard let timestamp = postInfo["timestamp"] as! Double! else return
let date = Date(timeIntervalSince1970: timestamp/1000)
guard let address = postInfo["businessStreet"] as! String! else return
guard let state = postInfo["businessCity"] as! String! else return
guard let postID = postInfo["postID"] as! String! else return
let lat = Double(postInfo["businessLatitude"] as! String)
let long = Double(postInfo["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 * 0.00062137
let distanceLabelText = String(format: "%.2f miles away", distanceInMiles)
let post = Post(uid: uid, caption: caption, downloadURL: downloadURL, name: name, date: date, address: address, state: state, distance: distanceLabelText, postID: postID)
self.feeds.append(post)
self.tableView.reloadData()
self.refreshControl?.endRefreshing()
self.feeds.sort $0.date.compare($1.date) == .orderedDescending
//self.feeds.sort $0.distance.compare($1.distance) == .orderedAscending
self.tableView.reloadData()
MBProgressHUD.hide(for: self.view, animated: true)
) (error) in
print(error.localizedDescription)
)
else
print("Not following anyone")
)
【问题讨论】：
【参考方案1】：当您从 firebase 调用的 api 调用返回时，您只是将结果附加到数组中，而不会删除旧内容。
在 fetchPostsWithLocation 方法中执行此操作，将结果添加到数组中：
self.following.removeAll()
self.following.append(user)
self.feeds.removeAll()
self.feeds.append(post)
然后重新加载您的表格视图。
【讨论】：
谢谢Badhan Ganesh，我总是对很明显的东西有问题 lmao以上是关于Swift Firebase UIRefreshControl 创建重复的帖子的主要内容，如果未能解决你的问题，请参考以下文章