UITableViewCell分隔线在滚动中消失

Question

I'm trying to have a separator cell with a custom image. I did try something like that:

In my cellForRowAtIndexPath:

NSString *cellIdentifier = [NSString stringWithFormat:@"identifier"];
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:cellIdentifier];
if (cell == nil) {
    cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:cellIdentifier];
}

cell.textLabel.font = [UIFont fontWithName:@"Helvetica" size:19];
cell.textLabel.text = [self.menuItems objectAtIndex:indexPath.row];
cell.textLabel.textColor = [UIColor colorWithRed:128/255.0f green:129/255.0f blue:132/255.0f alpha:1.0f];
cell.backgroundColor = [UIColor whiteColor];

UIImageView *imagView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"reaL.png"]];
imagView.frame = CGRectMake(0, cellHeight, cellWidth, 1);
[cell.contentView addSubview:imagView];

switch (indexPath.row) {
    case 0:
        cell.imageView.image = [self imageWithImage:[UIImage imageNamed:@"img1.png"] scaledToSize:CGSizeMake(27, 27)];
        cell.imageView.highlightedImage = [self imageWithImage:[UIImage imageNamed:@"route.png"] scaledToSize:CGSizeMake(27, 27)];
        break;
    case 1:
        cell.imageView.image = [self imageWithImage:[UIImage imageNamed:@"img.png"] scaledToSize:CGSizeMake(27, 27)];
        cell.imageView.highlightedImage = [self imageWithImage:[UIImage imageNamed:@"money.png"] scaledToSize:CGSizeMake(27, 27)];
        break;
    case 2:
        cell.imageView.image = [self imageWithImage:[UIImage imageNamed:@"auto.png"] scaledToSize:CGSizeMake(27, 27)];
        cell.imageView.highlightedImage = [self imageWithImage:[UIImage imageNamed:@"cars.png"] scaledToSize:CGSizeMake(27, 27)];
        break;
    case 3:
        cell.imageView.image = [self imageWithImage:[UIImage imageNamed:@"impostazioni.png"] scaledToSize:CGSizeMake(27, 27)];
        cell.imageView.highlightedImage = [self imageWithImage:[UIImage imageNamed:@"impostazioni.png"] scaledToSize:CGSizeMake(27, 27)];
       // cell.imageView.contentMode = UIViewContentModeScaleAspectFill;
        break;
    case 4:
        cell.imageView.image = [self imageWithImage:[UIImage imageNamed:@"info.png"] scaledToSize:CGSizeMake(27, 27)];
        cell.imageView.highlightedImage = [self imageWithImage:[UIImage imageNamed:@"info.png"] scaledToSize:CGSizeMake(27, 27)];
        break;
    default:
        break;
}

return cell;

When I lunch the app everything is good, but when I scroll the the table, or when I select a cell the separator lines disappear. How I can have a permanent custom line separator?

Answer 1

You're not creating cells properly in the first place. Here's a few tips to try that might help with the issue you're running into.

First off, since ios6, Apple now allows us to pre-register the classes we're using to dequeue cells so there is no more deed to do the !cell check. In your view did load, you'll want to do something akin to:

[self.tableView registerClass:[CustomTableViewCellClass class] forCellReuseIdentifier:customIdentifier];

This will allow you to dequeue the cell properly every time, as in:

UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:customIdentifier];

Next, and this is where I think you're running into issues. You're creating an image view and adding it to the cell every time the cell is dequeued.

UIImageView *imageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"reaL.png"]];
imageView.frame = CGRectMake(0, cellHeight, cellWidth, 1);
[cell.contentView addSubview:imageView];

You only need to do this the first time the cell is created otherwise you're going to be adding constantly UIImageViews to the top of the cell every time a cell is re-used. A better pattern for this situations would be to have a UIImageView* reference on the custom cell itself. When the cell is dequeue, set the image and frame then. This way the UIImageView is only created once and added to the cell once.

Best of luck!