heightForRowAtIndexPath for grouped UITableViewCell - ios

Question

I'm using the following method implementation to calculate the height of a UITableViewCell which is containing multiline text:
- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{
if (indexPath.section == 1 && indexPath.row == 1) {
NSDictionary *fields = self.messageDetailsDictionary[#"fields"];
NSString *cellText = fields[#"message_detail"];
UIFont *cellFont = [UIFont systemFontOfSize:14.0];
CGSize constraintSize = CGSizeMake(250.0f, MAXFLOAT);
CGSize labelSize = [cellText sizeWithFont:cellFont constrainedToSize:constraintSize lineBreakMode:NSLineBreakByWordWrapping];
return labelSize.height + 20;
} else {
return tableView.rowHeight;
}
}
For completeness, here's the cellForRowAtIndexPath entry for this cell:
UITableViewCell *cell = [[UITableViewCell new] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:#"DetailCell"];
if (cell == nil) {
cell = [[UITableViewCell new] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:#"DetailCell"];
}
cell.textLabel.lineBreakMode = NSLineBreakByWordWrapping;
cell.textLabel.font = [UIFont systemFontOfSize:14.0];
NSDictionary *fields = self.messageDetailsDictionary[#"fields"];
cell.textLabel.numberOfLines = 0; // This means multiline
cell.textLabel.text = fields[#"message_detail"];
return cell;
The UITableViewCell is in a Grouped UITableView, that's important because it affects the width of the cell.
This is working to the extent that it does calculate a cell height that is large enough to accomodate the text being input, but it seems to be a little too large as there is a little too much space at the top and bottom of the cell. This is dependent on the quantity of text so I don't think it's related to the return labelSize.height + 20; statement. I suspect this is down to the '250.0f' value I'm using in CGSizeMake but I don't know what the correct value should be here.
Ultimately what I want is to have a cell that has consistent padding above and below the text for any content size.
Can anyone help?

Answer 1

Through a process of elimination it turns out that the magic number is 270.0f.
The width of the tableView frame can be obtained from self.tableView.frame.size.width. This is 320.0f and taking 50.0f from this (equals to 270.0f) seems to produce consistent results.
So the method should be as follows:
- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{
if (indexPath.section == 1 && indexPath.row == 1) {
NSDictionary *fields = self.messageDetailsDictionary[#"fields"];
NSString *cellText = fields[#"message_detail"];
UIFont *cellFont = [UIFont systemFontOfSize:14.0];
CGSize constraintSize = CGSizeMake(self.tableView.frame.size.width - 50.0f, MAXFLOAT);
CGSize labelSize = [cellText sizeWithFont:cellFont constrainedToSize:constraintSize lineBreakMode:NSLineBreakByWordWrapping];
return labelSize.height + 20.0f;
} else {
return tableView.rowHeight;
}
}
I'm not exactly sure why 50.0f is the correct value, because I'm not sure how much of that 50.0f is the distance from the cell border to the tableView edge and how much of it is internal padding within the cell itself but it works unless you've amended either of those two values.