swift - 在表格 View 中显示后端服务的数据

Question

我正在从返回消息对象的后端服务获取数据，并且我想在 TableView 中显示消息。我遇到的问题是 View 加载和数据到达之间存在延迟。目前，一旦用户滚动表格 View ，消息就会显示。

override func viewDidLoad() {
    super.viewDidLoad()
    print("Message view did load")
    username = preferences.valueForKey("username") as! String
    userID = preferences.valueForKey("userID") as! String

    // Do any additional setup after loading the view.
    self.tableView.separatorStyle = UITableViewCellSeparatorStyle.None
    self.tableView.rowHeight = UITableViewAutomaticDimension

    getUser()
}

func getUser(){
    let currentUserAccessToken = EVUser.currentUser().accessToken
    EVUser.fetchWithAccessToken(currentUserAccessToken, block: { (loggedInUser:EVUser!, error:NSError!) -> Void in
        if (error == nil) {
            self.user = loggedInUser
            self.getMessages()
            print("The user " + loggedInUser.username + " is logged in with valid access token.")
        } else {
            print("The user is not logged in: " + error.domain)
        }
    })

}

func getMessages(){

    let dataStore: EVDataStore = EVDataStore.sharedInstance() as! EVDataStore

    //Filter item
    let request:EVFetchRequest = EVFetchRequest(kindOfClass: Message.self)

    request.predicate = NSPredicate(
        format: "CreatedByName == %@ OR (To == %@ AND CreatedByName == %@)",
        username,
        userID,
        "Admin"
    )
    dataStore.executeFetchRequest(request, block: { (result, error ) -> Void in
        if error == nil{
            if  result?.count > 0 {

                for item in result{
                    print (item)
                    self.globalMessages.append(item as! Message)
                }
                self.displayMessages(self.globalMessages)

            }else{
                print("No items found")
            }
        }else{
            print("Error: \(error)")
        }
    })
}


func displayMessages(messages:[Message]){
    setupTableView()
}


func setupTableView(){
    self.tableView.delegate = self;
    self.tableView.dataSource = self;
}

有没有办法在消息到达后立即将其添加到 TableView 中？

Answer 1

您有不止一种选择来执行此操作。无论您是重新加载整个表格 View 还是插入一行。

重新加载表格 View

tableView.reloadData()

插入行

tableView.beginUpdates()
tableView.insertRowsAtIndexPaths([NSIndexPath(forRow: {your message array}.count-1, inSection: 0)], withRowAnimation: .Automatic)
tableView.endUpdates()

有关更多信息，请查看此处:Insert new cell into UITableView