Question

如果我遵循此https://3v4l.org/8SSsN的建议并且使用DispatchQueue在主线程中调用reloadData（），则我的UITableView将仅显示单元格中的所有完全加载的内容。我在tableView cellForRowAt中执行此操作，因为它不会将我的数组中的值完全加载到所有单元格中。现在它不断重装，显然是非常耗能的。这使得在表视图中滚动更加困难，这是有道理的。

如何在我仍然需要的情况下将数据加载到单元格中时，如何防止这种荒谬的能量使用？

 func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {

    var cell:UITableViewCell? =
        charitiesSupportedTable?.dequeueReusableCell(withIdentifier: "SupportedCell")
    if (cell == nil)
    {
        cell = UITableViewCell(style: UITableViewCellStyle.subtitle,
                               reuseIdentifier: "abc")
    }


        if(indexPath.row <= moneyRaisedOfPrevPostsArray.count-1){
            cell?.textLabel?.text = charOfPrevPostsArray[indexPath.row]
            cell?.detailTextLabel?.text = moneyRaisedOfPrevPostsArray[indexPath.row]
        }

        DispatchQueue.main.async {
            self.charitiesSupportedTable.reloadData()
        }

    return cell!
}

这是我创建数组

的viewDidLoad

override func viewDidLoad() {
    super.viewDidLoad()


    let userEmail = Auth.auth().currentUser!.email
    var email1 = userEmail?.replacingOccurrences(of: "@", with: "", options: NSString.CompareOptions.literal, range:nil)
    email1 = email1?.replacingOccurrences(of: ".", with: "", options: NSString.CompareOptions.literal, range:nil)



    charitiesSupportedTable.delegate = self
    charitiesSupportedTable.dataSource = self

    charitiesSupportedTable.isScrollEnabled = false

    reff = Database.database().reference().child("Posts")

    let userRef1 =  reff?.queryOrdered(byChild: "user").queryEqual(toValue : email1)

    userRef1?.observe(.value, with: { (snapshot) in
        for child in snapshot.children {
            let snap = child as! DataSnapshot
            let key = snap.key
            let value = snap.value
            let valueAsDict = value as! NSDictionary


            charityOfPrevPosts = valueAsDict.value(forKey: "charity") as! String
            viewCountOfPrevPosts = valueAsDict.value(forKey: "viewCount") as! String // times .006
            moneyRaisedPrevPosts  = Double(viewCountOfPrevPosts)! * 0.006

            charOfPrevPostsArray.append(charityOfPrevPosts)
            moneyRaisedOfPrevPostsArray.append(String(moneyRaisedPrevPosts))



        }

        charOfPrevPostsArray.reverse()
        moneyRaisedOfPrevPostsArray.reverse()



    }
    )
    moneyRaisedOfPrevPostsArray.removeAll()
    charOfPrevPostsArray.removeAll()




    reff = Database.database().reference().child("UsersViews").child(email1!).child("totalMoneyRaised")
    reff?.observe(DataEventType.value, with: { (snapshot) in
        var totalMoney = snapshot.value as! Double

        self.totalMoneyLabel.text = String(format: "$%.02f", totalMoney)
    })

    // don't know if this part is relevant but I do return charitiesCount + 2 in numberOfRowsInSection
    reff = Database.database().reference()
    databaseHandle = reff?.child("UsersViews").child(email1!).child("charitiesSupported").observe(.value, with: { (snapshot) in

        let myDictionary11 = snapshot.value as? NSDictionary

        // Adds brands and charities to myData array
        for value in (myDictionary11?.allValues)! {
            self.myCharities.append(value as! String)
        }
        charitiesCount = self.myCharities.count

    })


}

UITableView reloadData（）使用来自cellForRowAt的大量功率调用

0 个答案: