iOS: uitableview redraw objects on first cell to bottom cells - ios

Question

i have a uitableview with custom cells.. with normal code
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"Cell";
DDMainCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];
if (cell == nil)
{
cell = [[DDMainCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
}
}
the problem is when i select one cell i add progress bar on the cell that download data online.. but when i Scroll down i find that every 10 cells have the same progress bar .. how can i prevent this behavior ?

Answer 1

Try this,
- (void)viewDidLoad
{
[super viewDidLoad];
dataarr=[[NSMutableArray alloc]init];
indexarr=[[NSMutableArray alloc]init];
mytableview=[[UITableView alloc]initWithFrame:self.view.bounds style:UITableViewStylePlain];
mytableview.dataSource=self;
mytableview.delegate=self;
[self.view addSubview:mytableview];
for (int i=0; i<30; i++) {
[dataarr addObject:[NSString stringWithFormat:#"%d",i]];
}
// Do any additional setup after loading the view, typically from a nib.
}
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
// Return the number of sections.
return 1;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
// Return the number of rows in the section.
return [dataarr count];
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier] ;
}
cell.textLabel.text=[dataarr objectAtIndex:indexPath.row];
UIActivityIndicatorView *act=[[UIActivityIndicatorView alloc]initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleGray];
[act setFrame:CGRectMake(50, 20, 20, 20)];
act.hidden=YES;
[cell.contentView addSubview:act];
cell.selectionStyle=UITableViewCellSelectionStyleNone;
if ([indexarr containsObject:[dataarr objectAtIndex:indexPath.row]])
{
[act startAnimating];
act.hidden=NO;
return cell;
}
return cell;
}
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
if ([indexarr containsObject:[dataarr objectAtIndex:indexPath.row]])
{
[mytableview reloadData];
return;
}
[indexarr addObject:[dataarr objectAtIndex:indexPath.row]];
[mytableview reloadData];
}
Make sure, when downloading is complete, then remove this object from indexarr....

Answer 2

That's because your cells are getting reused; UITableView will put off-screen cells into the reusable cell queue, and dequeue them for reuse if the reuseIdentifier matches. You should use some other data structure (e.g. NSArray or NSDictionary) to track which indices/cells have already been tapped. Then, in the method you showed above, regardless of whether the cell was init-ed or dequeued, set the progress bar according to your underlying data structure.

Answer 3

Here your used UITableViewCellIdentifier is reuseIdentifier. Which will work for all Cells are same type. Now your are taking once cell with progress bar. Now it will different from all cells data.
So use one more tableview cell for progress bar, or while reloading table remove the Progress bar which is exists already and add again. for this use tag for progress bar.