Asynchronous TableViewCell Data - ios

Question

I have a custom TableViewCell that I am getting data from a database in an asynchronous function that returns a UserObject that has the data I need in it. My problem is that the cellForRowAtIndexPath is returning the cell before that Asynchronous block is completed. How do i solve this problem?
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *simpleTableIdentifier = #"ImageWorkoutCellCollapsed";
ImageWorkoutCellCollapsed *cell = (ImageWorkoutCellCollapsed *)[tableView dequeueReusableCellWithIdentifier:simpleTableIdentifier];
if(cell == nil)
{
NSArray *nib = [[NSBundle mainBundle] loadNibNamed:#"ImageWorkoutCellCollapsed" owner:self options:nil];
cell = [nib objectAtIndex:0];
}
WorkoutObject *workout = [[WorkoutObject alloc]init];
workout = [appDelegate.workoutObjectsArray objectAtIndex:indexPath.row];
cell.workoutTitle.text = workout.workoutTitle;
cell.workoutViewCount.text = workout.workoutDescription;
__block UserObject *cellUserObject = [[UserObject alloc]init];
[dbPointer getUserObjectFromDB:workout.workoutOwnerID completion:^(UserObject *result)
{
cellUserObject = result;
}];
cell.userName.text = cellUserObject.username;
return cell;
}

Answer 1

You should turn the cell update into a reload of the row as follows:
1) You should use dequeueReusableCellWithIdentifier:forIndexPath rather than the version you are using.
2) You should not need to check (cell == nil) as 1) should never return nil.
3) Add a new NSMutableDictionary property to cache UserObject's by workoutOwnerID.
4) When you are asked for a cell, lookup the dictionary from 3) to see if it has your data object. if not, then run the DB query. If it has the object, set the cell values.
5) In your completion handler for the DB lookup, cache the returned object into the new dictionary by workoutOwnerID. Then simply request the table to reload the row.
The result is that the cells are updated when the data they represent is updated.

Answer 2

You should make sure cellForRowAtIndexPath is not being called before the data is available.
You have a count of the number of rows, you must be setting this count to N but you haven't yet fetched N data items.
Don't set this number until you have fetched all the data.
OR
As data arrives continually update the number or rows and refresh the table view.
OR
Return the cell with placeholder data. Then once the actual data for the cell is available update the content and refresh the table.
OR
All of the above solutions involves moving the data fetch out of cellForRowAtIndexPath. However IFF the call to fetch the data is quick and thus won't slow down the drawing of the table, you need to convert the fetch from being asynchronous to synchronous. But it is not good design for a view controller component to directly access a db, instead it should be going to a model and the model should abstract away the implementation detail that the data is in a database.