ios - Swift 远程搜索使 Tableview 崩溃

Question

嘿，我有一个 tableview，上面有一个搜索栏。我请求一个带有搜索词的远程 rest-api。搜索栏功能看起来像这样(根据这篇文章:How to throttle search (based on typing speed) in iOS UISearchBar?)

func searchBar(_ searchBar: UISearchBar, textDidChange searchText: String) {
    NSObject.cancelPreviousPerformRequests(withTarget: self, selector: #selector(self.searchTeams), object: nil)
    self.perform(#selector(self.searchTeams), with: nil, afterDelay: 0.3)
}

searchTeams-Func 看起来像这样，它调用带有完成处理程序的异步函数 loadingJSON:

loadingJSON("APIPATH", postString:"STRING") {
    parseJSON in

        if(String(describing: parseJSON) == "-1"){
            print("No Internet")
        } else {
            if let teams = parseJSON["teams"] as? [[String: AnyObject]] {
                self.teams.removeAll()

                for team in teams {
                   //Parse data
                }
                self.tableView.reloadData()

            }
        }
}

这几乎是完美的。但有时应用程序会在以下行的 cellForRowAt-indexPath-Methode 中崩溃:

teamSearchResultsCell.TeamNameLable.text = self.teams[indexPath.row].teamName

indexPath.row = 0 但团队数组为空。所以我认为如果用户在函数清除数组但尚未重新加载 tableview 的那一刻点击单元格，就会发生这种情况。有解决这个问题的想法吗？

编辑:为感兴趣的人加载 JSON-func:

func loadingJSON(_ link:String, postString:String, completionHandler: @escaping (_ JSONObject: AnyObject) -> ()) {
    if(Reachability.isConnectedToNetwork() == false){
        completionHandler("-1" as AnyObject)
        return
    }

    let request = NSMutableURLRequest(url: URL(string: FinalVars.getMobileRequestURL() + link)!)
    request.httpMethod = "POST"
    request.timeoutInterval = FinalVars.getRequestTimeoutIntervalInSeconds() //=7 Set Timeout in Seconds
    request.httpBody = postString.data(using: String.Encoding.utf8)

    let task = URLSession.shared.dataTask(with: request as URLRequest) { data, response, error in
        guard error == nil && data != nil else {
            //TimeOutReached --> No Network Connection
            print("error=\(String(describing: error))")

            DispatchQueue.main.async(execute: {
                completionHandler("-1" as AnyObject)
            })
            return
        }

        if let httpStatus = response as? HTTPURLResponse , httpStatus.statusCode != 200 {           // check for http errors
            print("statusCode should be 200, but is \(httpStatus.statusCode)")
            print("response = \(String(describing: response))")
        }

        //JSON successfull
        do {

            let parseJSON = try JSONSerialization.jsonObject(with: data!, options: .allowFragments)

            DispatchQueue.main.async(execute: {
                completionHandler(parseJSON as AnyObject)
            });


        } catch let error as NSError {
            print("Failed to load: \(error.localizedDescription)")

        }
    }
    task.resume() 
}

Answer 1

你应该有一条线来保证安全......

if teams.count > 0  { .. do your stuff ... } else { .. do nothing - there are no teams .. }

假设此后不久您的团队数组被填充，上面的行将帮助确保一切正常，直到网络响应用您的数据回复，然后一切都会很好。希望这会有所帮助。