UITableView Static Scrolling

Question

I have a simple UITableView using custom UITableViewCells. The options set on the UITableView's properties are only that the style is set to Grouped. When I'm trying to scroll down through the different items the scroll is extremely jumpy. I've researched this quite a bit looking at Tricks for improving iPhone UITableView scrolling performance? and a few other questions on this website. I haven't really been able to find a solution though.

EDIT **** I use a WSDL webservice to load data into the UITableViewCells. The cells only have a UITextView and three buttons in it.

EDIT ****

-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    static NSString *CellIdentifier = @"NavigatorCell";

    NewCell *cell = (NewCell *)[tableView dequeueReusableCellWithIdentifier:CellIdentifier];
    if (cell == nil) {
        NSArray *nib = [[NSBundle mainBundle] loadNibNamed:@"NewCell" owner:self options:nil];
        cell = [nib objectAtIndex:0];
    }

    cell.postId = [[items objectAtIndex:indexPath.row] objectForKey:@"PostID"];
    cell.post.text = [[items objectAtIndex:indexPath.row] objectForKey:@"Post"];

    return cell;
}

You should probably use some kind of "lazy loading". It's hard to be more specific since your question is, well, not specific. You might want to include some code (`cellForRowAtIndexPath:`) if you wish to get a good answer. — Rok Jarc, Apr 22 '13 at 21:21
@MarkM it is his items array. He is accessing the nib correctly — JeffN, Apr 22 '13 at 21:28
@StørmShadøws, you could improve the speed if you load the cell using `UINib` instead of `NSBundle`. — holex, Apr 22 '13 at 23:05

score 1 · Accepted Answer · answered Apr 22 '13 at 21:26

1

I see your NewCell is subclassed.

Don't forget to include this method into your NewCell.m

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

Of course @"Cell Identifier" should be the same that you use in your cellForRowAtIndexPath:. If you fail to implement this method each cell will be generated from scratch.

answered Apr 22 '13 at 21:26

Rok Jarc

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1

That fixed it! I can't thank you enough for helping me with this. – Destiny Dawn Apr 22 '13 at 21:28

score 0 · Answer 2 · answered Apr 22 '13 at 21:15

0

Are you using a dequeReusableCellWithIdentifier? Follow the format below. Since you now mention you are loading data from the web you need to do this asynchronously to allow for smooth scrolling. To load from a webservice (asynchronously) there is a nice project just for that here

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath     *)indexPath
{
    static NSString *CellIdentifier = @"yourCellName";
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];

    return cell;
}

answered Apr 22 '13 at 21:15

Mark McCorkle

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I load all of the data into a NSMutableArray, then use that arrow to fill the UITableView. – Destiny Dawn Apr 22 '13 at 21:17
You said you use a WSDL service to load into the cells. Are you loading to an array first? – Mark McCorkle Apr 22 '13 at 21:18
1

Post your cellForRowAtIndex please. – Mark McCorkle Apr 22 '13 at 21:20

score 0 · Answer 3 · answered Apr 22 '13 at 21:22

Setting your tableview to Reuse cells is the most basic way to ensure good performance. Basically it means that instead of creating a new cell for every cell in the tableview, your tableview will recycle the cells that are off screen. The basic setup is below, and more can be learned from the apple documentation on UITableViewDelegate linked here

       - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
        {
            NSString *CellIdentifier = @"Cell Identifier";

            CustomCellClassName *cell = (CustomCellClassName *)[tableView dequeueReusableCellWithIdentifier:CellIdentifier];

                if (cell == nil){
                    cell = [[CustomCellClassName alloc] initWithFrame:CGRectMake(0, 0, tableView.frame.size.width, tableView.frame.size.height)];
                    //Do basic cell construction common to all cells of this type here
                    //Set background, image etc.  
                }



                //Do specific cell construction here
                return cell;

That appears to be set up correctly, you will want to look at asynchronous loading of your data. Are you using standard Apple Networking for your data? Look into a library called AFNetworking on Github — JeffN, Apr 22 '13 at 21:25

score 0 · Answer 4 · answered Apr 22 '13 at 21:25

0

If you're loading data over the network for each cell, you'll see poor performance. Batch your data fetch, then when it's ready tell your tableview to reload itself.

Using Core Data as a temporary backing store, and an NSFetchedResultsController to retrieve the info from Core Data, will save you some work.

answered Apr 22 '13 at 21:25

Hal Mueller

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I'm loading it all into a NSMutableArray then the UITableView is getting handling it with the array. – Destiny Dawn Apr 22 '13 at 21:26

UITableView Static Scrolling

4 Answers4