Trying to calculate frame size of UILabel based on the amount of text for subview of cell

The code below has code that determines the frame size of a UILabel, and I think it does work, however when I place it within my rowAtIndexPath for a UItable I get wonky results.

Perhaps, I dont fully understand how or what the reuseIdentifier does, but I placed the code to calculate the frame only when the cell is nil. What happens is that the heights are calculated only for the first three cells, then it repeats in sequence for the rest of the cells. For example, cell one's height is used for cell four's height.

Maybe someone can point me in the right direction as to how I should setup my calculations.

Thanks!

if(cell == nil){

    cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault
                                reuseIdentifier:DisclosureButtonCellIdentifier] autorelease];

    //start adding custom subviews to the table cell


    //addSubview for Description
UILabel *descValue = [[UILabel alloc] init];
    NSString *descString = rowData.summary;
    CGSize maximumSize = CGSizeMake(185, 130);
    UIFont *descFont = [UIFont fontWithName:@"HelveticaNeue" size:12];
    CGSize descStringSize = [descString sizeWithFont:descFont 
                                   constrainedToSize:maximumSize 
                                       lineBreakMode:descValue.lineBreakMode开发者_StackOverflow中文版];
    CGRect descFrame = CGRectMake(125, 60, 185, descStringSize.height);
    descValue.frame = descFrame;

    descValue.backgroundColor = [UIColor redColor];
    descValue.font = descFont;
    descValue.tag = kDescriptionValueTag;
    descValue.lineBreakMode = UILineBreakModeWordWrap;
    descValue.numberOfLines = 0;

    [cell.contentView addSubview:descValue];
    [descValue release];
}


UILabel *desc = (UILabel *)[cell.contentView viewWithTag:kDescriptionValueTag];
    desc.text = rowData.summary;

Using NSString UIKit Additions, you can get the width of a string using a particular font:

[myString sizeWithFont:myFont];

There are several other functions in that Additions set that can help figure out how big a piece of text will be, with different layout options, for single and multi-line text, etc.

The purpose of the reuseIdentifier is to let you reuse a cell -- with particular subviews in particular places -- without the device having to spend the execution time to do all that layout. Definitely more useful back in the iPhone 1 days when the processor was much slower. Until you are more familiar with reuseIdentifiers, I would suggest you just create a new cell every time that function is called.

Each time the OS calls your cellForRowAtIndexPath, you need to fill out the content correctly. Anything that needs to get resized or changed depending on the row should be set.

Frankly, I did not try understanding your code completely. That is nearly impossible especially because you close the method with brackets without returning anything but cellForRowAtIndexPath which I assume you are referring to, requires the return of a UITableViewCell object.

Apparently we are looking only at some fraction of the code.

However, layouting a cell properly is not the full task. You need to tell the table the height of each cell. You may want to implement

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

for that task. That method is good if the cell height varies. If the cell hight is different from the standard but does not vary from cell to cell then setting of the rowHeight property of the tableView will be sufficient.

I think that in your case the implementation of the method heightForRowAtIndexPath is mandatory.

BTW, you may want to look at subclassing the UITableCellView and implement the layoutSubviews method in your subclass.

You didn't show all of your code but usually to implement tableView:cellForRowAtIndexPath: you start with the following:

-(UITableViewCell*)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    // get a cell from the queue of reusable cells, if any
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier: DisclosureButtonCellIdentifier];

    if (cell == nil) {
        // No cell to reuse, need to create a new one
        cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault
                                 reuseIdentifier:DisclosureButtonCellIdentifier] autorelease];  

        // add cell subviews here      
    }

    // fill in cell content and resize subviews here
    ...

    return cell;
}

Once you have created 3 (in your case) cells they get reused as the table scrolls so you don't have to keep creating cells. The call to dequeueReusableCellWithIdentifier will return one of the previously created cells if it was not longer in use (it scrolled off the top or the bottom).