我有一个带有某些单元格的表视图,每个单元格将从Internet获取数据。我的tableViewCell的功能:
override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
var cell = tableView.dequeueReusableCellWithIdentifier("placeCell", forIndexPath: indexPath) as! WeatherTableViewCell
......
//Create Url here...
......
let downloadTask: NSURLSessionDownloadTask = sharedSession.downloadTaskWithURL(url!, completionHandler: { (location: NSURL!, response: NSURLResponse!, error: NSError!) -> Void in
if error == nil {
let dataObject = NSData(contentsOfURL: location)
// println("dataObject:(dataObject)")
.........
// Got data text here
.........
println("dataText: (self.dataText)")
}
cell.label.text = "(self.dataText)"
})
downloadTask.resume()
return cell
}
一切正常,我可以为每个单元格获得所有数据,但是单元格的标签不会更新Datatext。当我获得每个单元格的数据时,我希望单元格更新Datatext。我该怎么做?
您必须在主线程中更新UI。
更换此:
cell.label.text = "(self.dataText)"
与此:
dispatch_async(dispatch_get_main_queue()) {
cell.label.text = "(self.dataText)"
}
请尝试。
var indexPath = NSIndexPath(forRow: 0, inSection: 0)
self.tableView.reloadRowsAtIndexPaths([indexPath], withRowAnimation: UITableViewRowAnimation.none)
您也可以使用以下代码以及
来达到您的要求// on main thread
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
// do your background code here
// schedule data download here
dispatch_sync(dispatch_get_main_queue(), ^{
// on main thread
// assign the text to label here
// also be sure to assign the text to label of current index path cell
});
});
[1]: http://stackoverflow.com/questions/30343678/how-can-i-reload-data-in-uitableviewcell-after-i-download-data-for-each-cell-fro?answertab=oldest#tab-top