ios - 使用UIRefreshControl刷新tableview

Question

我正在使用refreshcontrol，但是在我的代码编译时，当前代码存在一个问题，即它先删除所有数据，然后再提取表数据，这会导致片刻不显示任何数据的问题。有快速解决方案吗？我应该在帖子加载后通过调用removeAll来使用完成处理程序吗？

编辑:我已经在下面添加了fetchNetworkPost的相关部分。

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()

            })

        }
}

Answer 1

在完成fetchNetworkPosts()之后，调用您的refresh()，如下所示。检查下面的代码。

@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()

            })

        }
}