ios - 使用转义闭包对AlamoFire中的UITableViewData进行排序

Question

我正在尝试按字母顺序对带有自定义单元格的UTableView进行排序和分段。在我的ViewController中，我有一个下载JSON数据，然后将其存储在Dictionary中的函数。

var attendees = [Attendee]()
var sortedFirstLetters: [String] = []
var sections: [[Attendee]] = [[]]

func downloadAttendeeData(completed: @escaping DownloadComplete) {
    let headers: HTTPHeaders = [

        "Accept": "application/json;odata=verbose",
        "User-Agent": "iOS;iOS"

    ]

    NetworkManager.sharedInstance.manager.request(Attendee_URL, method: .get, headers: headers)
        .responseJSON { response in

            let result = response.result

            if let dict = result.value as? Dictionary<String, AnyObject> {

                if let list = dict["d"]?["results"] as? [Dictionary<String, AnyObject>] {

                    for att in list {
                        let attendee = Attendee(AttendeeDict: att)
                        self.attendees.append(attendee)

                    }


                    self.tableView.reloadData()

                }

            }

            completed()
    }


}

这段代码正是我所需要的

    let firstLetters = self.attendees.map { $0.titleFirstLetter }
    let uniqueFirstLetters = Array(Set(firstLetters))
    self.sortedFirstLetters = uniqueFirstLetters.sorted()

    self.sections = self.sortedFirstLetters.map { firstLetter in
        return self.names
            .filter { $0.titleFirstLetter == firstLetter }
            .sorted { $0.titleAD < $1.titleAD }
    }

但是，当我将这段代码放在viewDidLoad中时，它会生成和清空数组。

override func viewDidLoad() {
    super.viewDidLoad()


    tableView.delegate = self
    tableView.dataSource = self
    searchBar.delegate = self

    let firstLetters = self.attendees.map { $0.titleFirstLetter }
    let uniqueFirstLetters = Array(Set(firstLetters))
    self.sortedFirstLetters = uniqueFirstLetters.sorted()

    self.sections = self.sortedFirstLetters.map { firstLetter in
        return self.names
            .filter { $0.titleFirstLetter == firstLetter }
            .sorted { $0.titleAD < $1.titleAD }
    }

    self.downloadAttendeeData {


    }



}

如果我将代码放入self.downloadAttendeeData声明中，它将产生数据，但不会创建表节。

将数据加载到tableView后，如何生成节？那是问题吗？

Answer 1

确保从主线程调用tableView.reloadData()像这样:

dispatch_async(dispatch_get_main_queue()) { 
   self.tableView.reloadData()
}

或在Swift 3及更高版本中:

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