展开和折叠tableView单元格直到标签的文本

Question

我在TableViewCell中有一个标签，其中有多行文本。 最初在标签上只显示一行。 我在那个单元格上有一个按钮。 我想通过单击按钮直到标签文本的最高位置来扩展单元格。

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
   static NSString *CellIdentifier = @"tabCell";
   _cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];

// Configure the cell...
   NSManagedObject *device = [self.persons objectAtIndex:indexPath.row];

   UILabel *nameLabel = (UILabel*)[_cell.contentView viewWithTag:2];
  nameLabel.text = [NSString stringWithFormat:@"%@", [device valueForKey:@"name"]];

   UILabel *dateLabel = (UILabel *)[_cell.contentView viewWithTag:3];
   dateLabel.text = [NSString stringWithFormat:@"%@",[device valueForKey:@"date"]];

   UILabel *descLabel = (UILabel *)[_cell.contentView viewWithTag:4];
//descTextView.text = [NSString stringWithFormat:@"%@",[device valueForKey:@"desc"]];


   UIImageView *personImage = (UIImageView *)[_cell.contentView viewWithTag:1];
   UIImage *personImg = [UIImage imageWithData:[device valueForKey:@"image"]];
   personImage.image = personImg;

    UIButton *viewMoreButton = (UIButton *)[_cell.contentView viewWithTag:5];
    [viewMoreButton addTarget:self
             action:@selector(myAction)
   forControlEvents:UIControlEventTouchUpInside];

    NSAttributedString *attrString = [[NSAttributedString alloc] initWithString:[device valueForKey:@"desc"]
                                                                 attributes:@{ NSFontAttributeName:[UIFont fontWithName:@"HelveticaNeue" size:17]}];


    reqFrame=[attrString boundingRectWithSize:CGSizeMake(descLabel.frame.size.height, CGFLOAT_MAX)options:NSStringDrawingUsesLineFragmentOrigin
                                  context:nil];


    descLabel.attributedText = attrString;




    return _cell;
}

- (void)myAction{

   //what to write here?

}

Answer 1

首先，在cellForRowAtIndexPath构建单元不是一个好习惯。 请改用willDisplayCell 。 看看这里为什么 。

其次，要执行所需的操作，必须在heightForRowAtIndexPath设置所需的高度。 完成此操作后，您可以在按钮选择器调用中使用刷新特定单元格

[tableView reloadRowsAtIndexPaths:[NSArray arrayWithObjects:indexPathOfYourCell, nil] withRowAnimation:UITableViewRowAnimationAutomatic];

实现是类似的：

- (void)buttonSelector
{
    myLabel.text = @"YOUR TEXT";
    [myLabel sizeToFit];
    [tableView reloadRowsAtIndexPaths:[NSArray arrayWithObjects:indexPathOfYourCell, nil] withRowAnimation:UITableViewRowAnimationAutomatic];
}

-(CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath{
    ...
    return yourLabel.height;
}

Answer 2

无论如何，都需要获取myAction()在其上点击按钮的单元格和indexPath的 引用 。

创建一个私有变量CGFloat newCellHeight; 并将其初始化为0.0。 让对关联单元格的引用为selectedCell ，所选索引路径为indexPathOfTappedCell 。

- (void)myAction{
        UILabel *descLabel = (UILabel*)[selectedCell.contentView viewWithTag:4];
        [descLabel sizeToFit]; // Automatically increases the height of the label as required
        newCellHeight = CGRectGetMaxY(descLabel.frame) + 10.0; // Extra padding 10.0
        [tableView reloadRowsAtIndexPaths:@[indexPathOfTappedCell] withRowAnimation:UITableViewRowAnimationAutomatic];
}

现在在您的视图控制器中添加以下TableView委托方法

-(CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath{
    if (indexPath.section == indexPathOfTappedCell.section &&
        indexPath.row == indexPathOfTappedCell.row ) {
        return newCellHeight;
    }
    return 44.0; // Suppose default height is 44.0
}

Answer 3

您需要维护两个变量，只需给按钮添加标签，然后通过其标签进行操作以重新加载该特定单元格，然后使用另一个BOOL变量来检测按钮是否被触摸。 您应该在heightForRowAtIndexPath方法中计算高度。 我正在发布代码，可能会对您有所帮助

-(CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath{

if(isReadMoreButtonTouched && [indexPath row]== indexOfReadMoreButton) {
    NSString *yourText = [arr1 objectAtIndex:indexPath.row]; // your text

    NSDictionary *attributes = [NSDictionary dictionaryWithObjectsAndKeys:
                                [UIFont fontWithName:@"Avenir Next" size:14], NSFontAttributeName,
                                [UIColor grayColor], NSForegroundColorAttributeName,
                                nil]; // set custom attributes

    NSAttributedString *attributedText = [[NSAttributedString alloc] initWithString:yourText attributes:attributes];

    CGRect paragraphRect = [attributedText boundingRectWithSize:CGSizeMake(625, CGFLOAT_MAX)
                                                        options:(NSStringDrawingUsesLineFragmentOrigin|NSStringDrawingUsesFontLeading)
                                                        context:nil]; //here 625 is width of label

    NSLog(@"height = %f", paragraphRect.size.height);
    return paragraphRect.size.height;

}
else{

    return 200; //default height taken in storyboard
}
}


-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{

cell = [tableView dequeueReusableCellWithIdentifier:@"cell"];

cell.lblKB.text = [arr objectAtIndex:indexPath.row];
cell.lblDetail.text = [arr1 objectAtIndex:indexPath.row];

NSString *yourText = [arr1 objectAtIndex:indexPath.row];
NSDictionary *attributes = [NSDictionary dictionaryWithObjectsAndKeys:
                            [UIFont fontWithName:@"Avenir Next" size:14], NSFontAttributeName,
                            GrayColor, NSForegroundColorAttributeName,
                            nil];   //your custom attributes

NSAttributedString *attributedText = [[NSAttributedString alloc] initWithString:yourText attributes:attributes];

CGRect paragraphRect = [attributedText boundingRectWithSize:CGSizeMake(625, CGFLOAT_MAX)
                                                    options:(NSStringDrawingUsesLineFragmentOrigin|NSStringDrawingUsesFontLeading)
                                                    context:nil];

NSLog(@"height = %f", paragraphRect.size.height);

if (paragraphRect.size.height<200) {
    cell.btnMore.hidden = YES;
}
else{
    cell.btnMore.hidden = NO;
}

cell.btnMore.tag = indexPath.row;

return cell;
}


// action of button click

-(IBAction)MoreBtnClicked:(id)sender {

if (!isReadMoreButtonTouched) {
    isReadMoreButtonTouched = YES;
}
else{

    isReadMoreButtonTouched = NO;

}

indexOfReadMoreButton = [sender tag];

NSIndexPath *indexPath = [NSIndexPath indexPathForRow:[sender tag] inSection:0];
[self.tblKB reloadRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationAutomatic]; //reload that cell of your tableview

}