将UIViews添加到cell.contentView时，UITableView性能问题

基本上，当第一次初始化单元格时，我将按照Nishant的说明设置视图；但是，一旦单元被重用，我将提取需要更改的项目，例如UIImageView和UILabel.由于这些是指针，因此我可以在需要时修改自己需要的内容，并且性能又很快.这是我所做的缩写. -(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{静态NSString * NewsCellIdentifer = @"NewsCellIdentifier";NewsItem * item = [self.newsArray objectAtIndex:indexPath.row];UITableViewCell * cell = [tableView dequeueReusableCellWithIdentifier:NewsCellIdentifer];UIView * thumbNailMainView = [[UIView alloc] initWithFrame:CGRectMake(10，10，50，70)];UIImageView * thumbNail;UIView * textMainView = [[UIView分配] initWithFrame:CGRectMake(20,20,80,80)];UILabel * headerLabel = [[UILabel alloc] initWithFrame:CGRectMake(52，-5，70，20)];UILabel * teaserLabel = [[UILabel alloc] initWithFrame:CGRectMake(50,20，210，40)];UIView * newsItemCornerMainView = [[UIView alloc] initWithFrame:CGRectMake(255.7，55.2，55，55)]；UIImageView * cornerIconView;//如果该单元格不存在，则将其重新设置.如果(cell == nil){单元格= [[UITableViewCell分配] initWithStyle:UITableViewCellStyleDefault重用标识符:NewsCellIdentifer];//配置所有各种子视图.....//下面的示例//制作标题视图headerLabel.text = item.Title;CGFloat textfontSize = 16.0f;headerLabel.font = [BVFont Museo:& textfontSize];headerLabel.textColor = [BVColors WebBlue];headerLabel.textAlignment = NSTextAlignmentLeft;headerLabel.numberOfLines = 0;headerLabel.tag = 50;//制作预告片视图teaserLabel.text = item.Teaser;teaserLabel.numberOfLines = 0;CGFloat tfontSize = 13.0f;teaserLabel.textAlignment = NSTextAlignmentLeft;teaserLabel.textColor = [BVColors WebDarkGrey];teaserLabel.font = [BVFont HelveticaNeue:& tfontSize];[teaserLabel sizeToFit];teaserLabel.tag = 51;[textMainView addSubview:headerLabel];[textMainView sendSubviewToBack:headerLabel];[textMainView addSubview:teaserLabel];[cell.contentView addSubview:textMainView];....}thumbNail =(UIImageView *)[cell viewWithTag:47];[thumbNail setImage:[UIImage imageNamed:item.ThumbNailFileName]]；headerLabel =(UILabel *)[cell viewWithTag:50];headerLabel.text = item.Title;teaserLabel =(UILabel *)[cell viewWithTag:51];teaserLabel.text = item.Teaser;cornerIconView =(UIImageView *)[cell viewWithTag:48];[cornerIconView setImage:[UIImage imageNamed:item.CornerIconFileName]]；返回单元} I am experiencing performance problems when using some subviews on my UITableViewCells. After I keep scrolling it eventually starts getting very slow. First step I am doing is creating a common UIView for every cell, essentially this is creating a white cell with a rounded effect on the cell with a shadow. The performance for this seems to be normal so I don't think it's the culprit.Here is the code I am using to do this:- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{ static NSString *NewsCellIdentifer = @"NewsCellIdentifier"; NewsItem *item = [self.newsArray objectAtIndex:indexPath.row]; UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:NewsCellIdentifer]; if (cell == nil) { cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:NewsCellIdentifer]; cell.contentView.backgroundColor = [UIColor clearColor]; UIView *whiteRoundedCornerView = [[UIView alloc] initWithFrame:CGRectMake(10,10,300,100)]; whiteRoundedCornerView.backgroundColor = [UIColor whiteColor]; whiteRoundedCornerView.layer.masksToBounds = NO; whiteRoundedCornerView.layer.cornerRadius = 3.0; whiteRoundedCornerView.layer.shadowOffset = CGSizeMake(-1, 1); whiteRoundedCornerView.layer.shadowOpacity = 0.5; [cell.contentView addSubview:whiteRoundedCornerView]; [cell.contentView sendSubviewToBack:whiteRoundedCornerView]; cell.layer.shouldRasterize = YES; cell.layer.rasterizationScale = [UIScreen mainScreen].scale; cell.layer.opaque = YES; cell.opaque = YES; } [cell.contentView addSubview:[self NewsItemThumbnailView:item]]; return cell;}Here is the method that returns the thumbnail view of the graphic and text:- (UIView *) NewsItemThumbnailView:(NewsItem *)item{ UIView *thumbNailMainView = [[UIView alloc] initWithFrame:CGRectMake(10, 10, 50, 70)]; UIImageView *thumbNail = [[UIImageView alloc] initWithImage:[UIImage imageNamed:item.ThumbNailFileName]]; thumbNail.frame = CGRectMake(10,10, 45, 45); UILabel *date = [[UILabel alloc] init]; date.frame = CGRectMake(10, 53, 45, 12); date.text = item.ShortDateString; date.textAlignment = NSTextAlignmentCenter; date.textColor = [BVColors WebDarkGrey]; CGFloat fontSize = 10.0; date.font = [BVFont Museo:&fontSize]; date.opaque = YES; thumbNail.opaque = YES; thumbNailMainView.opaque = YES; [thumbNailMainView addSubview:thumbNail]; [thumbNailMainView addSubview:date]; return thumbNailMainView;}The performance problem seems to be when I add the thumbnail view to the cell because when I comment that line out, I don't seem to have it. The thumbnail information is dynamic and will change with each cell. I would appreciate any advice on how I should do this without degrading the performance. 解决方案 I ended up leveraging a solution found on this stackoverflow post: How should I addSubview to cell.contentView?Essentially when the cell is first initialized I am setting the view as mentioned by Nishant; however once the cell is reused I am extracting out the items I need to change, such as an UIImageView and then a UILabel. Since these are pointers I can modify just what I need when I need to and the performance is fast again. Here is a abbreviated version of what I did.- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{ static NSString *NewsCellIdentifer = @"NewsCellIdentifier"; NewsItem *item = [self.newsArray objectAtIndex:indexPath.row]; UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:NewsCellIdentifer]; UIView *thumbNailMainView = [[UIView alloc] initWithFrame:CGRectMake(10, 10, 50, 70)]; UIImageView *thumbNail; UIView *textMainView = [[UIView alloc] initWithFrame:CGRectMake(20,20,80,80)]; UILabel *headerLabel = [[UILabel alloc] initWithFrame:CGRectMake(52,-5, 70, 20)]; UILabel *teaserLabel = [[UILabel alloc] initWithFrame:CGRectMake(50,20, 210, 40)]; UIView *newsItemCornerMainView = [[UIView alloc] initWithFrame:CGRectMake(255.7, 55.2, 55, 55)]; UIImageView *cornerIconView; // If the cell doesn't existing go ahead and make it fresh. if (cell == nil) { cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:NewsCellIdentifer]; // Configure all the various subviews ..... //Sample below // Make the title view headerLabel.text = item.Title; CGFloat textfontSize = 16.0f; headerLabel.font = [BVFont Museo:&textfontSize]; headerLabel.textColor = [BVColors WebBlue]; headerLabel.textAlignment = NSTextAlignmentLeft; headerLabel.numberOfLines = 0; headerLabel.tag = 50; // Make the Teaser view teaserLabel.text = item.Teaser; teaserLabel.numberOfLines = 0; CGFloat tfontSize = 13.0f; teaserLabel.textAlignment = NSTextAlignmentLeft; teaserLabel.textColor = [BVColors WebDarkGrey]; teaserLabel.font = [BVFont HelveticaNeue:&tfontSize]; [teaserLabel sizeToFit]; teaserLabel.tag = 51; [textMainView addSubview:headerLabel]; [textMainView sendSubviewToBack:headerLabel]; [textMainView addSubview:teaserLabel]; [cell.contentView addSubview:textMainView]; .... } thumbNail = (UIImageView *) [cell viewWithTag:47]; [thumbNail setImage:[UIImage imageNamed:item.ThumbNailFileName]]; headerLabel = (UILabel *) [cell viewWithTag:50]; headerLabel.text = item.Title; teaserLabel = (UILabel *) [cell viewWithTag:51]; teaserLabel.text = item.Teaser; cornerIconView = (UIImageView *) [cell viewWithTag:48]; [cornerIconView setImage:[UIImage imageNamed:item.CornerIconFileName]]; return cell;} 这篇关于将UIViews添加到cell.contentView时，UITableView性能问题的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！