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iosswiftxcodeuitableviewpull-to-refresh
ml2008
ml2008

Reputation: 33

Refreshing tableview with UIRefreshControl

I'm using a refreshcontrol, but while my code compiles, the current code has an issue where it removes all the data first and then pulls in the table data causing a brief moment where it isn't showing any data. Is there a quick fix for this? Should I use a completion handler for this by calling removeAll once the posts are loaded...

Edit: I've added the relevant portion of fetchNetworkPost below.

override func viewDidLoad() {
super.viewDidLoad()

    let refreshControl = UIRefreshControl()
    refreshControl.addTarget(self, action: #selector(requestData), for: .valueChanged)

    self.refreshControl = refreshControl

    requestData()
}

@objc
func requestData() {

    self.postArray.removeAll()
    fetchNetworkPosts() //populates data

    refresh()

}

func refresh() {

  self.refreshControl?.endRefreshing()

  self.tableView.reloadData()

}

func fetchNetworkPosts() {

        for personId in networkArray {

    let currentUserRef = 
Database.database().reference().child("posts").queryOrdered(byChild: 
"userId").queryEqual(toValue: personId)
            currentUserRef.observeSingleEvent(of: .value, with: { 
(snapshot) in

                for childSnapshot in snapshot.children {

                    let test = Post(snapshot: childSnapshot as! DataSnapshot)

                    self.postArray.append(test)

                }

                self.postArray.sort { $0.postDate > $1.postDate } //sort

                self.tableView.reloadData()

            })

        }
}

Upvotes: 1

Views: 134

Answers (3)

Shabbir
Shabbir

Reputation: 299


override func viewDidLoad() {
    super.viewDidLoad()

    let refreshControl = UIRefreshControl()
    refreshControl.addTarget(self, action: #selector(requestData), for: .valueChanged)

    self.refreshControl = refreshControl

    requestData()
}
@objc func requestData() {
    fetchNetworkPosts() //populates data
}

func refresh() {

    self.refreshControl?.endRefreshing()

    self.tableView.reloadData()

}

func fetchNetworkPosts() {

    for personId in networkArray {

        let currentUserRef =
            Database.database().reference().child("posts").queryOrdered(byChild:
                "userId").queryEqual(toValue: personId)
        currentUserRef.observeSingleEvent(of: .value, with: {
            (snapshot) in

            self.postArray.removeAll()
            for childSnapshot in snapshot.children {

                let test = Post(snapshot: childSnapshot as! DataSnapshot)

                self.postArray.append(test)

            }

            self.postArray.sort { $0.postDate > $1.postDate } //sort

            self.refresh()

        })

    }
}

inside fetchNetworkPosts() method when you receive the new data self.postArray.removeAll() remove old data there and then assign new value at that time. then call refresh(). Hope this will work for you.

Upvotes: 1

Keshu R.
Keshu R.

Reputation: 5223

Call your refresh() after the completion of fetchNetworkPosts() like below. Check the code below.

@objc func requestData() {
    fetchNetworkPosts() //populates data
}

func refresh() {

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

}

func fetchNetworkPosts() {

         self.postArray.removeAll() // remove your array data here

        for personId in networkArray {

        let currentUserRef =
Database.database().reference().child("posts").queryOrdered(byChild:
"userId").queryEqual(toValue: personId)
            currentUserRef.observeSingleEvent(of: .value, with: {
(snapshot) in

                for childSnapshot in snapshot.children {

                    let test = Post(snapshot: childSnapshot as! DataSnapshot)

                    self.postArray.append(test)

                }

                self.postArray.sort { $0.postDate > $1.postDate } //sort

                self.refresh()

            })

        }
}

Upvotes: 1

Osman
Osman

Reputation: 71

maybe changing order will fix your problem.

override func viewDidLoad() {
super.viewDidLoad()

    let refreshControl = UIRefreshControl()
    refreshControl.addTarget(self, action: #selector(requestData), for: .valueChanged)

    self.refreshControl = refreshControl

    requestData()
}

@objc
func requestData() {


    fetchNetworkPosts() //populates data

    refresh()

}

func refresh() {
  self.postArray.removeAll()
  self.refreshControl?.endRefreshing()

  self.tableView.reloadData()

}

You are removing your data before fetch it. So, fetch data first then remove your tableView. You'll see your old data for brief time, not empty tableView.

Upvotes: 0

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