我已经对UITableViewCell进行了子类化,为其添加了自定义外观。在MYTableViewCell的init级别,我添加了4个子视图:UIImageView和三个UILabel。所有4个子视图都指定了不同的标记。
在cellForRowAtIndexPath方法中,如果一开始不可用,我要么创建一个新的单元格,要么重用可用的单元格并将正确的文本分配给ui标签。
我遇到的问题是,如果我试图以极快的速度滚动,那么数据就会变得一团糟,然而,如果我上下滚动得更慢,那么一切都会很好。
有什么想法吗??
以下是代码:
- (MyTableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = @"itemListTableViewCell";
MyTableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
DisplayableEntity *displayableEntity = [self.fetchedResultsController objectAtIndexPath:indexPath];
if( ! cell ) {
cell = [[MyTableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
[self tableView:tableView appearanceForCell:cell withEntity:displayableEntity];
} else {
UIImageView *imageView = (UIImageView *) [cell viewWithTag:IMAGEVIEW_TAG];
imageView.image = [UIImage imageNamed:displayableEntity.displayImageName];
UILabel *titleLabel = (UILabel *) [cell viewWithTag:TITLEVIEW_TAG];
titleLabel.text = displayableEntity.entityName;
UILabel *itemDescription = (UILabel *) [cell viewWithTag:DESCRIPTION_TAG];
itemDescription.text = displayableEntity.entityDesctiption;
}
}
// some code removed to make it brief
- (void)tableView:(UITableView *)tableView appearanceForCell:(MyTableViewCell *)cell withEntity:(DisplayableEntity *)entity {
// cell image view
UIImageView *cellImageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:[entity displayImageName]]];
[cellImageView setTag:IMAGEVIEW_TAG];
[cell addSubview:cellImageView];
// adding entity name label
UILabel *itemTitleName = [self itemTitleNameLabelWithFrame:itemNameLabelRect itemName:[entity entityName]];
[itemTitleName setTag:TITLEVIEW_TAG];
[cell addSubview:itemTitleName];
// adding 'assigned to' label right under the item name label
UILabel *itemDescriptionLabel = [self itemDescriptionLabelWithFrame:descriptionLabelFrame itemDescription:[entity entityDesctiption]];
[itemDescriptionLabel setTag:DESCRIPTION_TAG];
[cell addSubview:itemDescriptionLabel];
}
我在tableView:cellForRowAtIndexPath:
逻辑中看到一些问题应该是:
- 排队单元格
- 如果单元格无法出列-创建新单元格
- 设置所有单元格属性
我的意思是:
- (MyTableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = @"itemListTableViewCell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
} // <-- Note there is no else, we should reset properties in both cases
NSManagedObject *managedObject = [_fetchedResultsController objectAtIndexPath:indexPath];
cell.textLabel.text = [managedObject valueForKey:@"text"];
cell.imageView.image = [managedObject valueForKey:@"image"];
return cell;
}