Question

我已经实现了以下代码，它工作正常，它显示正确的数据，刷新时刷新。但是当快速向垃圾邮件发送垃圾邮件几次时，它最终会导致致命的错误 - 索引超出范围。

这让我发疯，有人能看出我的代码出了什么问题吗？

from StringIO import StringIO
import csv

res_io = StringIO()
header= ["review","id"]
csv_writer = csv.DictWriter(
    res_io,  fieldnames=header
    #delimiter=str(',')#, quoting=csv.QUOTE_NONNUMERIC
)
csv_writer.writerows([ {k:str(i[k]).replace("u'","'")}if type(i[k])==dict else {k:i[k]} for i in results for k in i ])

Answer 1

如果能解决这个问题，你能试试吗？因为这似乎是它崩溃的地方。

func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell
{
    let cell = tableView.dequeueReusableCell(withIdentifier: "cell") as! TableViewCell

    if nameArray.count > indexPath.row && addressArray.count > indexPath.row {
        cell.projectDesc.text = nameArray[indexPath.row].uppercased()
        cell.projectAddress.text = addressArray[indexPath.row]
    }
    return cell
}

添加if refresher.isRefreshing将阻止多次调用此数据请求。

func downloadJsonWithURL() {

    // If already refreshing don't run the code below
    if refresher.isRefreshing {

        // Emtpy arrays to avoid index out of range crash
        nameArray.removeAll(keepingCapacity: false)
        addressArray.removeAll(keepingCapacity: false)

        let url = NSURL(string: urlString)

        URLSession.shared.dataTask(with: (url as URL?)!, completionHandler: {(data, response, error) -> Void in


            if let jsonObj = try? JSONSerialization.jsonObject(with: data!, options: .allowFragments) as? NSDictionary {

                if let projectArray = jsonObj!.value(forKey: "project") as? NSArray {
                    for project in projectArray{
                        if let projectDict = project as? NSDictionary {
                            if let name = projectDict.value(forKey: "societe") {
                                self.nameArray.append(name as! String)
                            }
                        }
                        if let projectDict = project as? NSDictionary {
                            if let name = projectDict.value(forKey: "address") {
                                self.addressArray.append(name as! String)
                            }
                        }
                    }
                }

                OperationQueue.main.addOperation(
                    {
                        self.tableView.reloadData()
                        self.refresher.endRefreshing()
                })
            }
        }).resume()
    }
}

Answer 2

问题是您在接收响应之前是从数组中删除对象。它创建了一个场景，其中numberOfRowsInSection返回不同的值，并且在调用cellForRowAtIndexPath时，它在数组中有不同的（零）项，由于索引超出范围问题导致应用程序崩溃。这通常是多线程的问题。

要解决此问题，请仅在成功从API调用接收数据时清空阵列。为此，您需要在for project in projectArray{之上添加removeAll元素的代码。

使您的代码如下：

override func viewDidLoad()
{
    super.viewDidLoad()

    nameArray.removeAll(keepingCapacity: false)
    addressArray.removeAll(keepingCapacity: false)

    refresher = UIRefreshControl()
    refresher.attributedTitle = NSAttributedString(string: "Reloading")
    refresher.addTarget(self, action: #selector(downloadJsonWithURL), for: UIControlEvents.valueChanged)
    tableView.addSubview(refresher)
    self.downloadJsonWithURL()
}

func downloadJsonWithURL()
{
    let url = NSURL(string: urlString)

    URLSession.shared.dataTask(with: (url as URL?)!, completionHandler: {(data, response, error) -> Void in


        if let jsonObj = try? JSONSerialization.jsonObject(with: data!, options: .allowFragments) as? NSDictionary {

            if let projectArray = jsonObj!.value(forKey: "project") as? NSArray {
                nameArray.removeAll(keepingCapacity: false)
                addressArray.removeAll(keepingCapacity: false)

                for project in projectArray{
                    if let projectDict = project as? NSDictionary {
                        if let name = projectDict.value(forKey: "societe") {
                            self.nameArray.append(name as! String)
                        }
                    }
                    if let projectDict = project as? NSDictionary {
                        if let name = projectDict.value(forKey: "address") {
                            self.addressArray.append(name as! String)
                        }
                    }
                }
            }

            OperationQueue.main.addOperation(
                {
                    self.tableView.reloadData()
                    self.refresher.endRefreshing()
            })
        }
    }).resume()
}

表上的复习 - 索引超出范围错误

2 个答案: