ios - 调用 ViewController 时标签会重复

Question

我有一个带有 CoreData 和自定义单元格的 TableView，一切正常。

现在，当我选择一个单元格以编辑其内容并从中返回时，只需点击 UINavigationController 中的后退按钮，我就会发生一些奇怪的事情。

请看图片我的意思。似乎更新后的 UILabels 被放置在旧的 UILabels 之上而不是被“更新”？我错过了什么吗？？

您会在顶部单元格中看到差异，但它会发生在所有单元格中。

编辑:添加代码

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
 {
static NSString *cellIdentifier = @"Cell";

customCell = [_mainTableView dequeueReusableCellWithIdentifier:cellIdentifier forIndexPath:indexPath];
if (customCell == nil)
{
    customCell = [[MNCustomCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:cellIdentifier];

    CGRect frameTitle;
    frameTitle = CGRectMake(20, 4, 195, 21);

    CGRect frameSummary;
    frameSummary = CGRectMake(20, 25, 250, 30);

    CGRect frameDate;
    frameDate = CGRectMake(200, 4, 100, 21);

    MNotes *mnotes = [[self fetchedResultsController] objectAtIndexPath:indexPath];

    //Strings for Title and Summary
    titleString = mnotes.noteTitleString;
    summaryString = mnotes.mainNoteString;

    NSLog(@"TITLE STRING = %@", titleString);

    //Date
    SORelativeDateTransformer *relativeDateTransformer = [[SORelativeDateTransformer alloc] init];
    relativeDate = [relativeDateTransformer transformedValue:mnotes.createDate];

    customCell.noteTitle = [[UILabel alloc] initWithFrame:frameTitle];
    customCell.noteTitle.backgroundColor = [UIColor clearColor];
    customCell.noteTitle.font = [UIFont systemFontOfSize:20];
    customCell.noteTitle.userInteractionEnabled = NO;
    customCell.noteTitle.textColor = [self colorWithHexString:@"274D70"];

    customCell.noteSummary = [[UITextView alloc] initWithFrame:frameSummary];
    customCell.noteSummary.backgroundColor = [UIColor clearColor];
    customCell.noteSummary.font = [UIFont systemFontOfSize:10];
    customCell.noteSummary.userInteractionEnabled = NO;

    customCell.noteDate = [[UILabel alloc] initWithFrame:frameDate];
    customCell.noteDate.backgroundColor = [UIColor clearColor];
    customCell.noteDate.font = [UIFont systemFontOfSize:16];
    customCell.noteDate.userInteractionEnabled = NO;
    customCell.noteDate.textColor = [self colorWithHexString:@"274D70"]; //#274D70

}

customCell.noteTitle.text = titleString;
customCell.noteSummary.text = summaryString;
customCell.noteDate.text = relativeDate;

[customCell.contentView addSubview:customCell.noteTitle];
[customCell.contentView addSubview:customCell.noteSummary];
[customCell.contentView addSubview:customCell.noteDate];

 return customCell;
 }

Answer 1

UITableViews 通过回收单元格来工作。当 TableView 从它的委托(delegate)请求一个单元格时，如果有一个现有的未使用的单元格，它将使用它。否则它会分配一个新的。您应该只在分配新单元格时添加标签。如果它被回收，您只想设置现有标签的文本。

---

像这样:

    customCell.noteDate.textColor = [self colorWithHexString:@"274D70"]; //#274D70

    [customCell.contentView addSubview:customCell.noteTitle];
    [customCell.contentView addSubview:customCell.noteSummary];
    [customCell.contentView addSubview:customCell.noteDate];
    // try adding this:
    customCell.contentView.autoresizesSubviews = false;
}

customCell.noteTitle.text = titleString;
customCell.noteSummary.text = summaryString;
customCell.noteDate.text = relativeDate;

注意:实例化时，单元格的内容 View 和大小可能为 0,0。它可以在给定实际大小时调整 subview 的大小。

---

这看起来很奇怪...为什么不使用调用委托(delegate)的 tableView？像平常一样:

customCell = [tableView dequeueReusableCellWithIdentifier:cellIdentifier forIndexPath:indexPath];