如果我将titleTextView.backgroundColor = [UIColor clearColor]更改为任何其他颜色，它会显示我需要的颜色，但如果我保持原样，则覆盖所有[object objectForKey：@＆＃34; imageTitle＆＃34; ]值。
有没有人遇到过这样的问题？有什么建议吗？
这就是我现在正在做的事情。
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath object:(PFObject *)object {
static NSString *CellIdentifier = @"Cell";
NSUInteger index = [self indexForObjectAtIndexPath:indexPath];
if (indexPath.row % 2 == 0) {
// Header
return [self detailPhotoCellForRowAtIndexPath:indexPath];
} else {
// Photo
PhotoViewCell *cell = (PhotoViewCell *)[tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[PhotoViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
}
cell.photoButton.tag = index;
cell.imageView.image = [UIImage imageNamed:@"PlaceholderPhoto.png"];
if (object) {
UITextView * titleTextView = [[UITextView alloc]initWithFrame:CGRectMake(0, cell.imageView.bounds.size.width/2, cell.imageView.bounds.size.width, cell.imageView.bounds.size.width)];
cell.imageView.file = [object objectForKey:kPAPPhotoPictureKey];
titleTextView.backgroundColor = [UIColor clearColor];
titleTextView.text = [object objectForKey:@"imageTitle"];
titleTextView.font = [UIFont fontWithName:@"Arial" size:30];
titleTextView.textColor = [UIColor redColor];
[cell.contentView addSubview: titleTextView];
static NSString *CellIdentifier = @"footerCell";
PhotoFooterView *footerView = [self.tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (!footerView) {
footerView = [[PhotoFooterView alloc] initWithFrame:CGRectMake( 0.0f, cell.imageView.frame.size.height, self.view.bounds.size.width, 44.0f) buttons:PhotoFooterButtonsDefault];
footerView.delegate = self;
}
PFObject *object = [self objectAtIndexPath:indexPath];
footerView.photo = object;
footerView.tag = index;
[footerView.likeButton setTag:index];
NSDictionary *attributesForPhoto = [[APPCache sharedCache] attributesForPhoto:object];
if (attributesForPhoto) {
[footerView setLikeStatus:[[APPCache sharedCache] isPhotoLikedByCurrentUser:object]];
[footerView.likeButton setTitle:[[[APPCache sharedCache] likeCountForPhoto:object] description] forState:UIControlStateNormal];
[footerView.commentButton setTitle:[[[APPCache sharedCache] commentCountForPhoto:object] description] forState:UIControlStateNormal];
if (footerView.likeButton.alpha < 1.0f || footerView.commentButton.alpha < 1.0f) {
[UIView animateWithDuration:0.200f animations:^{
footerView.likeButton.alpha = 1.0f;
footerView.commentButton.alpha = 1.0f;
}];
}
} else {
footerView.likeButton.alpha = 0.0f;
footerView.commentButton.alpha = 0.0f;
@synchronized(self) {
// check if we can update the cache
NSNumber *outstandingSectionHeaderQueryStatus = [self.outstandingSectionHeaderQueries objectForKey:@(index)];
if (!outstandingSectionHeaderQueryStatus) {
PFQuery *query = [AAPUtility queryForActivitiesOnPhoto:object cachePolicy:kPFCachePolicyNetworkOnly];
[query findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error) {
@synchronized(self) {
[self.outstandingSectionHeaderQueries removeObjectForKey:@(index)];
if (error) {
return;
}
NSMutableArray *likers = [NSMutableArray array];
NSMutableArray *commenters = [NSMutableArray array];
BOOL isLikedByCurrentUser = NO;
for (PFObject *activity in objects) {
if ([[activity objectForKey:kPAPActivityTypeKey] isEqualToString:kPAPActivityTypeLike] && [activity objectForKey:kPAPActivityFromUserKey]) {
[likers addObject:[activity objectForKey:kPAPActivityFromUserKey]];
} else if ([[activity objectForKey:kPAPActivityTypeKey] isEqualToString:kPAPActivityTypeComment] && [activity objectForKey:kPAPActivityFromUserKey]) {
[commenters addObject:[activity objectForKey:kPAPActivityFromUserKey]];
}
if ([[[activity objectForKey:kPAPActivityFromUserKey] objectId] isEqualToString:[[PFUser currentUser] objectId]]) {
if ([[activity objectForKey:kPAPActivityTypeKey] isEqualToString:kPAPActivityTypeLike]) {
isLikedByCurrentUser = YES;
}
}
}
[[APPCache sharedCache] setAttributesForPhoto:object likers:likers commenters:commenters likedByCurrentUser:isLikedByCurrentUser];
if (footerView.tag != index) {
return;
}
[footerView setLikeStatus:[[APPCache sharedCache] isPhotoLikedByCurrentUser:object]];
[footerView.likeButton setTitle:[[[APPCache sharedCache] likeCountForPhoto:object] description] forState:UIControlStateNormal];
[footerView.commentButton setTitle:[[[APPCache sharedCache] commentCountForPhoto:object] description] forState:UIControlStateNormal];
if (footerView.likeButton.alpha < 1.0f || footerView.commentButton.alpha < 1.0f) {
[UIView animateWithDuration:0.200f animations:^{
footerView.likeButton.alpha = 1.0f;
footerView.commentButton.alpha = 1.0f;
}];
}
}
}];
}
}
}
[cell addSubview:footerView];
// PFQTVC will take care of asynchronously downloading files, but will only load them when the tableview is not moving. If the data is there, let's load it right away.
if ([cell.imageView.file isDataAvailable]) {
[cell.imageView loadInBackground];
}
}
return cell;
}
}
提前致谢
答案 0 :(得分：0)
问题是UITableView单元格被重用。当一个单元格从表格的边缘滚动时，＆＃34; new＆＃34;在另一侧取代它的单元格实际上是同一个对象（在视图创建和销毁方面可以节省大量成本）。
dequeueReusableCellWithIdentifier:返回其中一个单元格，大部分时间从滚动位置重复使用。您的cellForRowAtIndexPath每次都会添加一个文本视图 ，这意味着大多数情况下它都是在文本视图中堆叠文本视图。清晰的颜色背景让您注意到错误。
修复是有条件地构建文本视图，只有当单元格还没有，就像这样......
// your existing code up to here
UITextView *titleTextView = (UITextView *)[cell viewWithTag:99];
// this condition guards against building another text view when you have one already
if (!textView) {
titleTextView = [[UITextView alloc]initWithFrame: // and so on
// so we can find it later in the viewWithTag line above
titleTextView.tag = 99;
// your code to build the text view here, but not the line
// that sets the text. we do that unconditionally for every cell
[cell.contentView addSubview: titleTextView];
}
// this part of the view varies by cell, so do it unconditionally...
titleTextView.text = [object objectForKey:@"imageTitle"];
// your existing code from here
顺便说一句，你cellForRowAtIndexPath方法的其余部分是漫长且非标准的，两个警告标志着前方的麻烦。第二次打电话给＃34; footerView＆＃34;我特别感到困惑。
在没有先检查您是否已经获取数据的情况下，在此方法中启动异步调用绝对是不明智的。请记住，当用户滚动相同的单元格时，会快速调用此方法。出于同样的原因，您只需为每个单元格构建一个文本视图，您需要一个防护来确保每个单元格的单个请求（或更少）。
解决这个问题的第一步是将所有与模型相关的代码移出数据源方法。让模型缓存结果，如果已经获取结果，立即返回完成。