UICollectionView在重新加载数据时不平滑地滚动
UICollectionView在重新加载数据时不平滑地滚动
提问于 2016-12-09 10:30:43
在我的UICollecitonView中，我使用
self.DataTableCollectionView.reloadData()
但是，随着我的集合中的数据越来越多，它的滚动变得粗糙，在加载了一些页面之后，就很难向上或向下滚动。它被卡住了。
最后，当我尝试一次加载1000行时，滚动工作平稳，但是当我尝试使用API一次分页并加载50行时，就很难滚动。
有谁能帮我解决这个问题？
我搞不清是怎么回事？self.DataTableCollectionView.reloadData()可对此作出响应吗？
下面是加载滚动数据的代码：
func scrollViewDidScroll(scrollView: UIScrollView) {
let offsetY = scrollView.contentOffset.y
let contentHeight = scrollView.contentSize.height
if(offsetY > (contentHeight - scrollView.frame.size.height)){
let seconds = 3.0
let delay = seconds * Double(NSEC_PER_SEC)
let dispatchTime = dispatch_time(DISPATCH_TIME_NOW, Int64(delay))
self.loadMoreData()
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), {
self.DataTableCollectionView.reloadData()
})
}
}==========
我在重复使用这些细胞
self.DataTableCollectionView .registerNib(UINib(nibName: "DCollectionViewCell", bundle: nil), forCellWithReuseIdentifier: dCellIdentifier)
self.DataTableCollectionView .registerNib(UINib(nibName: "CCollectionViewCell", bundle: nil), forCellWithReuseIdentifier: cCellIdentifier) 以及重复使用：
func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
let dCell : DCollectionViewCell = collectionView .dequeueReusableCellWithReuseIdentifier(dCellIdentifier, forIndexPath: indexPath) as! DCollectionViewCell
let cCell : ContentCollectionViewCell = collectionView .dequeueReusableCellWithReuseIdentifier(cCellIdentifier, forIndexPath: indexPath) as! CCollectionViewCell
}=========
添加更具体的代码：
现在我更新了我的滚动功能
func scrollViewDidScroll(scrollView: UIScrollView) {
let offsetY = scrollView.contentOffset.y
let contentHeight = scrollView.contentSize.height
if(offsetY > (contentHeight - scrollView.frame.size.height)){
var returnTableData = NSMutableArray()
self.InspectPageId = self.InspectPageId+1
self.dataSource.populateData(PageId:self.InspectPageId)
returnTableData = self.dataSource.DTableDataArray
if(returnTableData.count>0){
for i in 0..<returnTableData.count {
self.TableDataArray.addObject(returnTableData[i])
}
}
self.NumberOfRows = self.TableDataArray.count
dispatch_async(dispatch_get_main_queue(),{
self.DataTableCollectionView.reloadData()
})
}
}以下是手动创建集合视图的代码：
if indexPath.row == 0 {
//Here Header Cell is creating
let dateCell : DateCollectionViewCell = collectionView .dequeueReusableCellWithReuseIdentifier(dateCellIdentifier, forIndexPath: indexPath) as! DateCollectionViewCell
dateCell.dateLabel.font = UIFont(name:"HelveticaNeue", size: 12)
dateCell.dateLabel.textColor = UIColor.blackColor()
dateCell.dateLabel.textAlignment = .Left
dateCell.dateLabel.text = UMIDDataArray[rowIndex-1] as? String
dateCell.backgroundColor = UIColor.whiteColor()
dateCell.layer.shouldRasterize = true
dateCell.layer.rasterizationScale = UIScreen.mainScreen().scale
return dateCell
} else {
//Here Data Cell is Creating
let contentCell : ContentCollectionViewCell = collectionView .dequeueReusableCellWithReuseIdentifier(contentCellIdentifier, forIndexPath: indexPath) as! ContentCollectionViewCell
contentCell.contentLabel.font = UIFont(name:"HelveticaNeue", size: 12)
contentCell.contentLabel.textColor = UIColor.blackColor()
contentCell.contentLabel.textAlignment = .Left
contentCell.bottomBorder.hidden = false
contentCell.layer.shouldRasterize = true
contentCell.layer.rasterizationScale = UIScreen.mainScreen().scale
let LensData:NSArray = TableDataArray[rowIndex-1] as! NSArray
let ColumnValue = LensData[colIndex-1] as? String
contentCell.contentLabel.text = ColumnValue
contentCell.backgroundColor = UIColor.whiteColor()
return contentCell
}
Following is the code which is use to take data from API:
//function of DataSource Class.
func populateData(PageId:Int){
var returnData = NSMutableArray()
let OtherColobjects = NSMutableArray()
let Urlpath = SetApiUrl()
let url: NSURL = NSURL(string: Urlpath)!
let urlRequest = NSURLRequest(URL: url)
let config = NSURLSessionConfiguration.defaultSessionConfiguration()
let session = NSURLSession(configuration: config)
let semaphore = dispatch_semaphore_create(0)
let task = session.dataTaskWithRequest(urlRequest) {
(data, response, error) in
guard error == nil else {
return
}
guard let responseData = data else {
return
}
do {
guard let Data = try NSJSONSerialization.JSONObjectWithData(responseData, options: []) as? [String: AnyObject] else {
return
}
for anItem in Data["result"]!["DATA"] as! [Dictionary<String, AnyObject>] {
let d1 = self.checkForNull(anItem["data1"]!)
let d2 = self.checkForNull(anItem["data2"]!)
let d3 = self.checkForNull(anItem["data3"]!)
let d4 = self.checkForNull(anItem["data4"]!)
...... // Total 20 Columns
let obj = [ d1, d2, d3, d4,.............,d20 ]
OtherColobjects.addObject(obj)
}
dispatch_semaphore_signal(semaphore)
} catch {
return
}
}
task.resume()
dispatch_semaphore_wait(semaphore, DISPATCH_TIME_FOREVER)
self.NumberOfRows = returnData[0].count
self.DTableDataArray = returnData[1] as! NSMutableArray
}回答 6
Stack Overflow用户
回答已采纳
发布于 2016-12-13 04:42:34
您应该只从主线程更新您的UI，所以请这样做.
Swift 2.x：
dispatch_async(dispatch_get_main_queue()), {
self.DataTableCollectionView.reloadData()
}Swift 3：
DispatchQueue.main.async {
self.DataTableCollectionView.reloadData()
}如果这不能解决问题，那么您可能还需要在后台线程上调用loadMoreData() .
Swift 2.x：
dispatch_async(dispatch_get_global_queue(QOS_CLASS_UTILITY, 0)){
self.loadMoreData()
}Swift 3：
DispatchQueue.global(qos: DispatchQoS.QoSClass.default).async {
self.loadMoreData()
}还不清楚您的代码是如何工作的，因为您还没有向我们展示您的loadMoreData()函数。实际上，这似乎意味着从DataTableCollectionView.reloadData()内部调用loadMoreData，但我无法在没有看到函数的情况下判断。请添加附加代码
Stack Overflow用户
发布于 2016-12-09 11:32:13
在排队列单元格后添加以下2行，
cell.layer.shouldRasterize = YES;
cell.layer.rasterizationScale = [UIScreen mainScreen].scale;Stack Overflow用户
发布于 2016-12-09 10:35:33
您应该将reloadData()发送到MainThread上。根据苹果的文档，操作UI应该总是在MainThread中完成。
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/41058298
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