在Swift中，我使用Segmented Controller根据选择的细分来填充TableView JSON JSON。两个self.tableView .reloadData()文件都加载成功，因为在我的第一个文件中有两个单元格，在我的第二个文件中有3个。当我单击第二个段时，在当前查看的两个单元格下方，出现第三个。问题是，尽管我Segmented Controller的{{1}} IBAction和我的viewWillAppear函数调用class MainVC: UIViewController, UITableViewDelegate, UITableViewDataSource {
@IBOutlet var tableView: UITableView!
var dataArray: NSArray = NSArray()
@IBOutlet var Controller: UISegmentedControl!
override func viewWillAppear(animated: Bool) {
self.tableView .reloadData()
}
override func viewDidLoad() {
super.viewDidLoad()
startConnectionAt("http://www.domain.com")
// Do any additional setup after loading the view.
}
@IBAction func Change(sender: AnyObject) {
if Controller.selectedSegmentIndex == 0 {
startConnectionAt("http://www.domain.com")
}
else if Controller.selectedSegmentIndex == 1 {
startConnectionAt("http://www.domain.com")
}
self.tableView .reloadData()
}
//MARK: JSON Loading
var data: NSMutableData = NSMutableData()
func startConnectionAt(urlPath: String){
var url: NSURL = NSURL(string: urlPath)
var request: NSURLRequest = NSURLRequest(URL: url)
var connection: NSURLConnection = NSURLConnection(request: request, delegate: self, startImmediately: false)
connection.start()
}
func connection(connection: NSURLConnection!, didFailWithError error: NSError!) {
println("Connection failed.\(error.localizedDescription)")
}
func connection(connection: NSURLConnection, didRecieveResponse response: NSURLResponse) {
println("Recieved response")
}
func connection(didReceiveResponse: NSURLConnection!, didReceiveResponse response: NSURLResponse!) {
self.data = NSMutableData()
}
func connection(connection: NSURLConnection!, didReceiveData data: NSData!) {
self.data.appendData(data)
}
func connectionDidFinishLoading(connection: NSURLConnection!) {
var dataAsString: NSString = NSString(data: self.data, encoding: NSUTF8StringEncoding)
var err: NSError
var json: NSDictionary = NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions.MutableContainers, error: nil) as NSDictionary
var results: NSArray = json["needs"] as NSArray
self.dataArray = results
tableView.reloadData()
println("success")
}
//End loading of JSON
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
func tableView(tableView: UITableView!, numberOfRowsInSection section: Int) -> Int {
return self.dataArray.count;
}
func tableView(tableView: UITableView!, cellForRowAtIndexPath indexPath: NSIndexPath!) -> UITableViewCell! {
var cell:CustomCell = self.tableView.dequeueReusableCellWithIdentifier("cell") as CustomCell
var rowData: NSDictionary = dataArray[indexPath.row] as NSDictionary
var title=rowData["needFirstname"] as String
var poster=rowData["needCountry"] as String
var descrip=rowData["needDescription"] as String
//GDC
var queue=dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0)
dispatch_async(queue, {
cell.needTitle.text = title
cell.needPoster.text = poster
cell.needDescription.text = descrip
cell.needDescription.numberOfLines = 0
})
return cell
}
}
，但上面的两个版本都没有重新加载。
单击单元格后，相应的信息会显示出来并且一切正常，但直到我单击该行为止。是什么给了什么？
我的MainVC.swift文件
class CustomCell: UITableViewCell {
@IBOutlet var needTitle: UILabel!
@IBOutlet var needPoster: UILabel!
@IBOutlet var needDescription: UILabel!
}
我的CustomClass.swift文件（用于自定义UITableViewCell）
{{1}}
答案 0 :(得分：4)
问题是您在后台线程上设置了单元格的UI元素，在这里：
//GDC
var queue=dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0)
dispatch_async(queue, {
cell.needTitle.text = title
cell.needPoster.text = poster
cell.needDescription.text = descrip
cell.needDescription.numberOfLines = 0
})
我不确定你为什么要使用GCD调度到那里的后台队列，但你不应该这样做。 所有UI元素必须始终从主线程/队列更新。
简单地摆脱你的dispatch_async它应该有效：
func tableView(tableView: UITableView!, cellForRowAtIndexPath indexPath: NSIndexPath!) -> UITableViewCell! {
var cell:CustomCell = self.tableView.dequeueReusableCellWithIdentifier("cell") as CustomCell
var rowData: NSDictionary = dataArray[indexPath.row] as NSDictionary
var title=rowData["needFirstname"] as String
var poster=rowData["needCountry"] as String
var descrip=rowData["needDescription"] as String
cell.needTitle.text = title
cell.needPoster.text = poster
cell.needDescription.text = descrip
cell.needDescription.numberOfLines = 0
return cell
}