Loading a Reusable UITableViewCell from a Nib

Question

I am able to design custom UITableViewCells and load them just fine using the technique described in the thread found at http://forums.macrumors.com/showthread.php?t=545061.

Answer 1

Actually, since you are building the cell in Interface Builder, just set the reuse identifier there:

Or if you are running Xcode 4, check the Attributes inspector tab:

(Edit: After your XIB is generated by XCode, it contains an empty UIView, but we need a UITableViewCell; so you have to manually remove the UIView and insert a Table View Cell. Of course, IB will not show any UITableViewCell parameters for a UIView.)

Answer 2

From the UITableView docs regarding dequeueWithReuseIdentifier: "A string identifying the cell object to be reused. By default, a reusable cell’s identifier is its class name, but you can change it to any arbitrary value."

Overriding -reuseIdentifer yourself is risky. What happens if you have two subclasses of your cell subclass, and use both of these in a single table view? If they send the reuse identifier call onto super you'll dequeue a cell of the wrong type.............. I think you need to override the reuseIdentifier method, but have it return a supplanted identifier string. Or, if one has not been specified, have it return the class as a string.

Answer 3

Just implement a method with the appropriate method signature:

- (NSString *) reuseIdentifier {
  return @"myIdentifier";
}

Answer 4

Here is another option:

NSString * cellId = @"reuseCell";  
//...
NSArray * nibObjects = [[NSBundle mainBundle] loadNibNamed:@"CustomTableCell" owner:nil options:nil];

for (id obj in nibObjects)
{
    if ([obj isKindOfClass:[CustomTableCell class]])
    {
        cell = obj;
        [cell setValue:cellId forKey:@"reuseIdentifier"];
        break;
    }
}

Answer 5

This technique also works and doesn't require a funky ivar in your view controller for memory management. Here, the custom table view cell lives in a xib named "CustomCell.xib".

 static NSData *sLoadedCustomCell = nil;

 cell = [tableView dequeueReusableCellWithIdentifier:@"CustomCell"];
 if (cell == nil) 
 {
   if (sLoadedCustomCell == nil) 
   {        
      // Load the custom table cell xib
      // and extract a reference to the cell object returned
      // and cache it in a static to avoid reloading the nib again.

      for (id loadedObject in [[NSBundle mainBundle] loadNibNamed:@"CustomCell" owner:nil options:nil]) 
      {
        if ([loadedObject isKindOfClass:[UITableViewCell class]]) 
        {
          sLoadedCustomCell = [[NSKeyedArchiver archivedDataWithRootObject: loadedObject] retain];
          break;
        }
    }
    cell = (UITableViewCell *)[NSKeyedUnarchiver unarchiveObjectWithData: sLoadedCustomCell];
  }

Answer 6

For what it's worth, I asked an iPhone engineer about this at one of the iPhone Tech Talks. His answer was, "Yes, it's possible to use IB to create cells. But don't. Please, don't."