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UITableViewCell - how to reset content before reuse

There is an annoying mistake that I cannot fix.

I have a CustomCell , and in it I have a subview that changes color depending on the value of the object.

 - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { static NSString *cellIdentifier = @"CustomCell"; CustomCell *cell = (CustomCell *)[tableView dequeueReusableCellWithIdentifier:cellIdentifier forIndexPath:indexPath]; if (cell == nil) { cell = [[CustomCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:cellIdentifier]; } MyObject *object = [self.fetchedResultsController objectAtIndexPath:indexPath]; if ([object.redColor isEqualToNumber:[NSNumber numberWithBool:YES]]) { cell.colorView.backgroundColor = [UIColor redColor]; } else { cell.colorView.backgroundColor = [UIColor clearColor]; } return cell; }

Everything works fine, except when I delete the row with redColor = YES from the table view and I scan to show rows that were not visible. The first row that becomes visible (the first row that reuses a reused cell) is red, although this row is redColor = NO . And if I scroll again and hide the cell and then show it again, the color will be set to clearColor, as it should be.

I think this is due to the fact that it reuses the cell just removed. Therefore, before reusing, I try to use the contents of reset. In CustomCell.m

 - (void)prepareForReuse { [super prepareForReuse]; self.clearsContextBeforeDrawing = YES; self.contentView.clearsContextBeforeDrawing = YES; self.colorView.backgroundColor = [UIColor clearColor]; }

But that does not work. Apple Doc says

Divide the table delegate in tableView: cellForRowAtIndexPath: should always reset all content when reusing a cell.

What is the correct way to keep reset? Do I need to remove subviews from the supervisor?

Thank you in advance

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3 answers

This seems to work.

I delete the contents of the cellView when preparing CustomCell.m in CustomCell.m

 - (void)prepareForReuse { [super prepareForReuse]; // Clear contentView BOOL hasContentView = [self.subviews containsObject:self.contentView]; if (hasContentView) { [self.contentView removeFromSuperview]; } }

Add it again to cellForRowAtIndexPath

 - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { // Cell static NSString *cellIdentifier = @"CustomCell"; CustomCell *cell = (CustomCell *)[tableView dequeueReusableCellWithIdentifier:cellIdentifier forIndexPath:indexPath]; if (cell == nil) { cell = [[CustomCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:cellIdentifier]; } // Restore contentView BOOL hasContentView = [cell.subviews containsObject:cell.contentView]; if (!hasContentView) { [cell addSubview:cell.contentView]; } // Configure cell MyObject *object = [self.fetchedResultsController objectAtIndexPath:indexPath]; if ([object.redColor isEqualToNumber:[NSNumber numberWithBool:YES]]) { cell.colorView.backgroundColor = [UIColor redColor]; } else { cell.colorView.backgroundColor = [UIColor clearColor]; } return cell; }

Hope this helps someone.

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You can use this tableview delegate method to change visibility (e.g. background color) but not data:

 - (void)tableView:(UITableView *)tableView willDisplayCell:(UITableViewCell *)cell forRowAtIndexPath:(NSIndexPath *)indexPath
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  - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { NSString *cellIdentifier = [NSString stringWithFormat:@"CustomCell %ld",(long)indexPath.row]; CustomCell *cell = (CustomCell *)[tableView dequeueReusableCellWithIdentifier:cellIdentifier]; cell = nil; if (cell == nil) { cell = [[CustomCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:cellIdentifier]; MyObject *object = [self.fetchedResultsController objectAtIndexPath:indexPath]; if ([object.redColor isEqualToNumber:[NSNumber numberWithBool:YES]]) { cell.colorView.backgroundColor = [UIColor redColor]; } else { cell.colorView.backgroundColor = [UIColor clearColor]; } return cell; }
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