UITableView custom cell images disappear after scrolling.

问题

I am in the process of creating my open grid view.

I created a custom cell that looks like so:

I handle populating it like so:

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

    TableGalleryCustomCell *cell = (TableGalleryCustomCell*)[tableView dequeueReusableCellWithIdentifier:MyIdentifier];

    if( cell == nil) {
        NSArray *topLevelObjects = [[NSBundle mainBundle] loadNibNamed:@"TableGalleryCustomCell" owner:nil options:nil];
        for (id currentObject in topLevelObjects) {
            if ([currentObject isKindOfClass:[UITableViewCell class]]) {
                cell = (TableGalleryCustomCell*)currentObject;
                break;
            }
        }
    }

    if (countingIndex < [[[self.appDelegate rssParser] rssItems] count]) {
        cell.firstAddress.text = [[[[self.appDelegate rssParser] rssItems] objectAtIndex:countingIndex] Address];
        cell.firstPrice.text = [[[[self.appDelegate rssParser] rssItems] objectAtIndex:countingIndex] Deposit];
        if ([[[[[[self appDelegate] rssParser]rssItems]objectAtIndex:countingIndex] imageURLs] count] != 0 ) {
            [cell.firstImage setImageWithURL:[NSURL URLWithString:[[[[[self.appDelegate rssParser] rssItems] objectAtIndex:countingIndex] imageURLs] objectAtIndex:0.0]]];
            cell.firstImage.tag = countingIndex;
        }
    }

    countingIndex++;
    if (countingIndex < [[[self.appDelegate rssParser] rssItems] count]) {
        cell.secondAddress.text = [[[[self.appDelegate rssParser] rssItems] objectAtIndex:countingIndex] Address];
        cell.secondPrice.text = [[[[self.appDelegate rssParser] rssItems] objectAtIndex:countingIndex] Deposit];
        if ([[[[[[self appDelegate] rssParser]rssItems]objectAtIndex:countingIndex] imageURLs] count] != 0 ) {
            [cell.secondImage setImageWithURL:[NSURL URLWithString:[[[[[self.appDelegate rssParser] rssItems] objectAtIndex:countingIndex] imageURLs] objectAtIndex:0.0]]];
            cell.secondImage.tag = countingIndex;
        }
    }

    countingIndex++;
    if (countingIndex < [[[self.appDelegate rssParser] rssItems] count]) {
        cell.thirdAddress.text = [[[[self.appDelegate rssParser] rssItems] objectAtIndex:countingIndex] Address];
        cell.thirdPrice.text = [[[[self.appDelegate rssParser] rssItems] objectAtIndex:countingIndex] Deposit];
        if ([[[[[[self appDelegate] rssParser]rssItems]objectAtIndex:countingIndex] imageURLs] count] != 0 ) {
            [cell.thirdImage setImageWithURL:[NSURL URLWithString:[[[[[self.appDelegate rssParser] rssItems] objectAtIndex:countingIndex] imageURLs] objectAtIndex:0.0]]];
            cell.thirdImage.tag = countingIndex;
        }
    }

    countingIndex++;
    if (countingIndex < [[[self.appDelegate rssParser] rssItems] count]) {
        cell.fourthAddress.text = [[[[self.appDelegate rssParser] rssItems] objectAtIndex:countingIndex] Address];
        cell.fourthPrice.text = [[[[self.appDelegate rssParser] rssItems] objectAtIndex:countingIndex] Deposit];
        if ([[[[[[self appDelegate] rssParser]rssItems]objectAtIndex:countingIndex] imageURLs] count] != 0 ) {
            [cell.fourthImage setImageWithURL:[NSURL URLWithString:[[[[[self.appDelegate rssParser] rssItems] objectAtIndex:countingIndex] imageURLs] objectAtIndex:0.0]]];
            cell.fourthImage.tag = countingIndex;
        }
    }

    countingIndex++;


    return cell;
}

It is a bit messy but it works.....until I scroll. After the image is loaded then scrolled off the screen the image disappears.

I believe that it maybe due to the imageViews of the cells being lost?

I tried the exact same implementation but with only 1 imageView in each cell and all works great.

Any point in the right direction would be very much appreciated.

I appreciate any help and thank you for your time.

回答1:

I believe the problem is because your cells are being dequeued and you are populating cells in tableView:cellForRowAtIndexPath: using row information other than the indexPath.row.

Maybe try something along the following lines:

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    NSArray         * rssItems;
    id                rssItem;
    static NSString * MyIdentifier = @"Cell";

    TableGalleryCustomCell *cell = (TableGalleryCustomCell*)[tableView dequeueReusableCellWithIdentifier:MyIdentifier];

    if( cell == nil) {
        NSArray *topLevelObjects = [[NSBundle mainBundle] loadNibNamed:@"TableGalleryCustomCell" owner:nil options:nil];
        for (id currentObject in topLevelObjects) {
            if ([currentObject isKindOfClass:[UITableViewCell class]]) {
                cell = (TableGalleryCustomCell*)currentObject;
                break;
            }
        }
    }

    rssItems =  [[self.appDelegate rssParser] rssItems];
    if (indexPath.row < [rssItems count]) {
        rssItem = [rssItems objectAtIndex:indexPath.row];
        cell.firstAddress.text = [rssItem Address];
        cell.firstPrice.text   = [rssItem Deposit];
        if ([[rssItem imageURLs] count] != 0 ) {
            [cell.firstImage setImageWithURL:[NSURL URLWithString:[[rssItem imageURLs] objectAtIndex:0.0]]];
            cell.firstImage.tag = indexPath.row;
        }
    }

    return cell;
}

回答2:

Sharing my experience:

Had similar problems. I have many tables in the app, and in one of them data would randomly disappear, and eventually the entire table would go away.

The problem for me was that I was dequeueing cells, giving all of them the same "unique" id. So several tables were sharing the same id, and I believe they were conflicting and messing up the cells I was looking at.

Giving each table it's own unique identifier solved the problem for me. (dah!)

来源：https://stackoverflow.com/questions/8981366/uitableview-custom-cell-images-disappear-after-scrolling

标签

objective-c

ios

gridview

uitableview