UITableView: load all cells - objective-c

Question

Is it possible to load all cells of an UITableView when the view is loaded so that they are not loaded when I'm scrolling?
(I would show a loading screen while doing this)
Please, it's the only way at my project (sorry too complicate to explain why ^^)
EDIT:
Okay let me explain you, what I'm definite doing:
- (UITableViewCell *)tableView:(UITableView *)tableView
cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
NSString *cellIdentifier = [NSString stringWithFormat:#"Identifier %i/%i", indexPath.row, indexPath.section];
CustomTableCell *cell = (CustomTableCell *)[tableView dequeueReusableCellWithIdentifier:cellIdentifier];
NSDictionary *currentReading;
if (cell == nil)
{
cell = [[[CustomTableCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:cellIdentifier] autorelease];
UILabel *label;
UIView *separator;
if(indexPath.row == 0)
{
// Here I'm creating the title bar of my "table" for each section
}
else
{
int iPr = 1;
do
{
currentReading = [listData objectAtIndex:iPr-1];
iPr++;
} while (![[currentReading valueForKey:#"DeviceNo"] isEqualToString:[devicesArr objectAtIndex:indexPath.section]] ||
[readingresultsArr containsObject:[currentReading valueForKey:#"ReadingResultId"]]);
[readingresultsArr addObject:[currentReading valueForKey:#"ReadingResultId"]];
//
// ...
//
}
}
return cell;
}
My error happens in the do-while-loop:
"listData" is an array with multiple dictionaries in it.
My problem ist that when I’m scrolling my table slowly down, all is fine, but when I’m scrolling quickly to the end of the view and then I’m scrolling to the middle, I get the error that iPr is out of the array’s range. So the problem is, that the last row of the first section has already been added to the "readingresultsArr", but has not been loaded or wants to be loaded again.
That’s the reason why I want to load all cells at once.

Answer 1

You can cause all of the cells to be pre-allocated simply by calling:
[self tableView: self.tableView cellForRowAtIndexPath: indexPath];
for every row in your table. Put the above line in an appropriate for-loop and execute this code in viewDidAppear.
The problem however is that the tableView will not retain all of these cells. It will discard them when they are not needed.
You can get around that problem by adding an NSMutableArray to your UIViewController and then cache all the cells as they are created in cellForRowAtIndexPath. If there are dynamic updates (insertions/deletions) to your table over its lifetime, you will have to update the cache array as well.

Answer 2

put a uitableview on a uiscrollview
for example , you expect the height of the full list uitableview is 1000
then set the uiscrollview contentsize is 320X1000
and set the uitableview height is 1000
then all cell load their content even not visible in screen

Answer 3

In my case it was that I used automaticDimension for cells height and put estimatedRowHeight to small that is why tableview loaded all cells.

Answer 4

Some of the answers here and here suggest using automaticDimension for cells height and put mytable.estimatedRowHeight to a very low value (such as 1).
Starting with iOS 15 this approach seems not to work anymore. Hence, another way to achieve the table to "load" all cells could be by automatically scrolling to the last cell. Depending on the tables height and how many rows it can show some cells are discarded but each cell would be loaded and shown at least once.
mytable.scrollEnabled = YES;
NSIndexPath* indexPath = [NSIndexPath indexPathForRow:cellCount - 1 inSection:0];
[mytable scrollToRowAtIndexPath:indexPath atScrollPosition:UITableViewScrollPositionBottom animated:YES];
mytable.scrollEnabled = NO;
If you want to scroll up again just scroll to the top as outlined here.

Answer 5

Following the comment that was made by juancazalla, I found that if you have a tableView that is using automaticDimension, loading all the cells at once can be best achieved by setting estimatedRowHeight to a low value (such as 1).