Para altura dinâmica da minha célula de exibição de tabela, tomo referência neste link.Usando o Layout automático no UITableView para layouts de células dinâmicos e alturas de linhas variáveis

Aqui está o meu código de fonte de dados tableview e métodos delegados

-(NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section;
  {
       return arrTemp. count;
  }

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

AutoLayoutTableViewCell *cell=(AutoLayoutTableViewCell *)[tableView dequeueReusableCellWithIdentifier:cellIdentifier];
if (cell==nil) {
    for (id currentObject in [[NSBundle mainBundle] loadNibNamed:@"AutoLayoutTableViewCell" owner:self options:nil]) {
        if ([currentObject isKindOfClass:[UITableViewCell class]]) {
            cell = (AutoLayoutTableViewCell *)currentObject;
            break;
        }
    }
}

cell.IBlblLineNo.text=[NSString stringWithFormat:@"Line:%i",indexPath.row];
cell.IBlblLineText.text=[arrTemp objectAtIndex:indexPath.row];
[cell setNeedsUpdateConstraints];
[cell updateConstraintsIfNeeded];

CGSize expectedlineLabelSize = [cell.IBlblLineText.text sizeWithFont:cell.IBlblLineText.font constrainedToSize:CGSizeMake(280, 1000) lineBreakMode:NSLineBreakByTruncatingTail];
cell.IBlblLineText.numberOfLines=expectedlineLabelSize.height/17;

CGRect frmlbl=cell.IBlblLineText.frame;
frmlbl.size.height=expectedlineLabelSize.height;
cell.IBlblLineText.frame=frmlbl;

return cell;
}

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

AutoLayoutTableViewCell *cell = (AutoLayoutTableViewCell *)[IBtblAutoLayoutExample cellForRowAtIndexPath:indexPath];

cell.IBlblLineNo.text=[NSString stringWithFormat:@"Line:%i",indexPath.row];
cell.IBlblLineText.text=[arrTemp objectAtIndex:indexPath.row];

[cell setNeedsUpdateConstraints];
[cell updateConstraintsIfNeeded];

CGSize expectedlineLabelSize = [cell.lineLabel.text sizeWithFont:cell.lineLabel.font constrainedToSize:CGSizeMake(280, 1000) lineBreakMode:NSLineBreakByWordWrapping];

 cell.IBlblLineText.numberOfLines=expectedlineLabelSize.height/17;
CGRect frmlbl=cell.IBlblLineText.frame;
frmlbl.size.height=expectedlineLabelSize.height;
cell.IBlblLineText.frame=frmlbl;

CGFloat height = [cell.contentView systemLayoutSizeFittingSize:UILayoutFittingCompressedSize].height;
height += 1.0f;

return height;
}

- (CGFloat)tableView:(UITableView *)tableView estimatedHeightForRowAtIndexPath:(NSIndexPath *)indexPath
{
     AutoLayoutTableViewCell *cell = (AutoLayoutTableViewCell *)[IBtblAutoLayoutExample cellForRowAtIndexPath:indexPath];

 CGSize expectedlineLabelSize = [cell.IBlblLineText.text sizeWithFont:cell.IBlblLineText.font constrainedToSize:CGSizeMake(280, 1000) lineBreakMode:NSLineBreakByTruncatingTail];

 return expectedlineLabelSize.height;

}

Eu tenho 2 perguntas:

Meu problema é que recebo o erroEXE_BAD_EXCESS perto da linha

AutoLayoutTableViewCell *cell = (AutoLayoutTableViewCell *)[IBtblAutoLayoutExample cellForRowAtIndexPath:indexPath]; 

noheightForRowAtIndexPath eestimatedHeightForRowAtIndexPath.

Por que tenho que escrever o texto da etiqueta nos doiscellForRowAtIndexPath eheightForRowAtIndexPath?

Além disso, estou faltando alguma coisa necessária para atingir a altura dinâmica da célula?