tableview单元无法正确更新

Question

I am using table view to show downloaded songs.I am creating empty folder before downloading song without extinction ".mp3" after downloading song I am replacing that file with original file which has extinction of .mp3 .now aim getting files on music folder and shooing it in table view. The table view shows activity indicator in cell before downloading song. After downloading song i replace the activity indicator by a button by hiding it. My problem is after downloading the file it was not able to replace the button but it hid the indicator. even though i scrolled the button doesn't appear. Whenever i close that view controller and return back to download list it shows properly. after downloading file i tried [tableview reload data]; but no change.

any help would be appreciated iam usingI am using table view to show downloaded songs. The table view shows activity indicator in cell before downloading song. After downloading song i replace the activity indicator by a button by hiding it. My problem is after downloading the file it was not able to replace the button but it hid the indicator. even though i scrolled the button doesn't appear. Whenever i close that view controller and return back to download list it shows properly. after downloading file i tried [tableview reload data]; but no change.

any help would be appreciated

                             if((![[songName substringFromIndex:MAX((int)            [songName length]-4, 0)] isEqualToString:@".mp3"])    
       {        
CoustoumCell *cellMain = [tableView dequeueReusableCellWithIdentifier:@"cell" forIndexPath:indexPath];           
    cellMain.backgroundView=[[UIImageView alloc] initWithImage:[UIImage imageNamed:@"Table-view-background.png"]];           
 cellMain.AlbumLable.textColor = [UIColor colorWithRed:0.278 green:0.278  blue:0.278 alpha:1.0];
cellMain.selectedBackgroundView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"Table-view-selected-background.png"]];
cellMain.indiCatorForDon.tag=indexPath.row;
[cellMain.indiCatorForDon startAnimating];
[cellMain.playButton removeFromSuperview];

cellMain.imageView.image=Nil;
cellMain.downloadStatusLable.text=@"Downloading....";
cellMain.AlbumLable.text=[_songsList objectAtIndex:indexPath.row];
cellMain.numberLable.text=[NSString stringWithFormat:@"%d",indexPath.row+1];
}
   else
{
CoustoumCell *cellMain = [tableView dequeueReusableCellWithIdentifier:@"cell" forIndexPath:indexPath];
cellMain.backgroundView=[[UIImageView alloc] initWithImage:[UIImage imageNamed:@"Table-view-background.png"]];
cellMain.AlbumLable.textColor = [UIColor colorWithRed:0.278 green:0.278    blue:0.278 alpha:1.0];
cellMain.selectedBackgroundView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"Table-view-selected-background.png"]];
cellMain.AlbumLable.text=[_songsList objectAtIndex:indexPath.row];
    [cellMain.indiCatorForDon stopAnimating];
cellMain.downloadStatusLable.textColor = [UIColor colorWithRed:0.278 green:0.278 blue:0.278 alpha:1.0];
cellMain.sizeLable.textColor = [UIColor colorWithRed:0.278 green:0.278 blue:0.278 alpha:1.0];
cellMain.sizeLable.text=[[self getSize] objectAtIndex:indexPath.row];
cellMain.downloadStatusLable.text=@"Downloaded";
cellMain.completedImage.image=[UIImage imageNamed:@"checked.png"];
    cellMain.numberLable.text=[NSString stringWithFormat:@"%d",indexPath.row+1];
cellMain.playButton.tag=indexPath.row;
}
    return cellMain;

after downloading song sending notification from another view to table view

  - (void) receiveTestNotification:(NSNotification *) notification
{
   if ([[notification name] isEqualToString:@"TestNotification"])
         {
           NSLog (@"Successfully received the test notification!");

    // Perform long running process
       [self  updateDownloadList];
       [[AlbumsAnsSongs sharedManager] getallFiles];
       [_tableView reloadData];
   }
 }

Answer 1

Since problem is with UI update so I guess when your data completes downloading you should call reloadData method like this:

 - (void) receiveTestNotification:(NSNotification *) notification
{
   if ([[notification name] isEqualToString:@"TestNotification"])
         {
           NSLog (@"Successfully received the test notification!");

    // Perform long running process
       [self  updateDownloadList];
       [[AlbumsAnsSongs sharedManager] getallFiles];

       dispatch_async(dispatch_get_main_queue(), ^(void){
            [_tableView reloadData];
        });

   }
 }

Another problem that seems to be there is that you are removing the button with this statement

[cellMain.playButton removeFromSuperview];

but in else part you are not adding the button back,

I think instead of removing playButton you should hide the button

cellMain.playButton.hidden = YES

and then in else part

cellMain.playButton.hidden = NO

Explanation:

You were removing the button from cell, since the cells are dequed or you can say reused , cells without button were being displayed on the screen