cellForRowAtIndexPath和Cell Configuration

Question

Okay, so consumate with the standard template code for UITableViewController, I've been using cellForRowAtIndexPath: to set up my UITableViewCells based on the data source.

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
//cell setup
cell.textLabel.text = @"Initial Data!";
return cell;
}

However, this is suddenly striking me as a problematic practice. For instance, lets say I want to do this

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
  //some processing or data update is done here
  //now I want to update the cell
  UITableViewCell *cell = [tableView cellForRowAtIndexPath:indexPath];
  cell.textLabel.text = @"New Data";
}

It seems like this is wasteful code, because retrieving the cell to update it, is causing it to be updated a second time from the code in cellForRowAtIndexPath.

So should I be putting the configuration for the cell somewhere else and calling it some other way, or should I be writing the configuration in cellForRowAtIndexPath in a more clever way so that a simple call to it will update the UI withou

Answer 1

Maybe altering the data is a better idea.

I'm assuming you will get your data from an array? Then alter the data in the didSelectRowAtIndexPath method and reload just the selected cell.

Answer 2

Generally I keep a self array to apply necessary data to cell.

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
   //cell setup
   MyObject *obj = ...; ///< retrieve obj from somewhere
   cell.textLabel.text = obj.text;
   return cell;
}

Then, when selected, I will modify my data source.

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {

    NSString *newData = @"New Data";  ///<  

    // Update data source 
    MyObject *obj = ...;
    obj.text = newData;

    // Update UI
    ....
}

I prefer to make MyObject to handle things about data processing, for example, obtain a thumbnail for cell in a thread, or calculate complexity result. Controller will combine data and UI.