我已经实现了下面的代码,它们工作正常,它显示正确的数据,并在拉动后刷新。但是,当将垃圾邮件快速发送几次时,最终会导致致命错误-索引超出范围。
这让我发疯,有人可以看到我的代码有什么问题吗?
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()
{
// 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()
}
// Count length of array and create number of cells accordingly
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int
{
return nameArray.count
}
// Create cell data from arrays
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell
{
let cell = tableView.dequeueReusableCell(withIdentifier: "cell") as! TableViewCell
cell.projectDesc.text = nameArray[indexPath.row].uppercased()
cell.projectAddress.text = addressArray[indexPath.row]
return cell
}
最佳答案
问题是您要在接收响应之前从阵列中删除对象。它创建了一个场景,其中numberOfRowsInSection
返回不同的值,并且在调用cellForRowAtIndexPath
时,它在数组中具有不同的(零)项,由于索引超出范围问题,导致应用程序崩溃。这通常是多线程问题。
为解决此问题,仅当成功从API调用接收数据时,才清空数组。为此,您需要在for project in projectArray{
上方添加removeAll元素的代码。
,使您的代码类似于:
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()
}