每次滚动tableview时，单元格中的图像都会改变

Question

In the below code whenever I am scrolling the tableview, images in each cell are changing, which shouldn't happen. Please help. Thanks in advance.

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{
UserDetails *userDetails = [arrUserDetails objectAtIndex:indexPath.row];
static NSString *CellIdentifier = @"CustomCell";
__weak TableViewCell *cell = (TableViewCell *)[_tableViewUsername dequeueReusableCellWithIdentifier:CellIdentifier];
cell.tag = indexPath.row;
cell.userName.text = userDetails.userName;
   [self.operationQueue addOperationWithBlock: ^ {  
    NSURL *aURL = [NSURL URLWithString:userDetails.userImageURL];
    NSError *error = nil;
    NSData *data = [NSData dataWithContentsOfURL:aURL options:nil error:&error];
    UIImage *image = nil;
    if (cell.tag == indexPath.row)
    {
        image = [UIImage imageWithData:data];
        [[NSOperationQueue mainQueue] addOperationWithBlock: ^ {
            cell.customImageView.image = image;
            cell.customImageView.contentMode = UIViewContentModeScaleToFill;
            cell.accessoryType = UITableViewCellAccessoryCheckmark;
        }];
    }
}];

Answer 1

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{
UserDetails *userDetails = [arrUserDetails objectAtIndex:indexPath.row];
static NSString *CellIdentifier = @"CustomCell";
__weak TableViewCell *cell = (TableViewCell *)[_tableViewUsername dequeueReusableCellWithIdentifier:CellIdentifier];
cell.tag = indexPath.row;
cell.userName.text = userDetails.userName;

//Add Default placeholder
cell.customImageView.image = [UIImage imageNamed:@"Default.png"];

   [self.operationQueue addOperationWithBlock: ^ {  
    NSURL *aURL = [NSURL URLWithString:userDetails.userImageURL];
    NSError *error = nil;
    NSData *data = [NSData dataWithContentsOfURL:aURL options:nil error:&error];
    UIImage *image = nil;
    if (cell.tag == indexPath.row)
    {
        image = [UIImage imageWithData:data];
        [[NSOperationQueue mainQueue] addOperationWithBlock: ^ {
            cell.customImageView.image = image;
            cell.customImageView.contentMode = UIViewContentModeScaleToFill;
            cell.accessoryType = UITableViewCellAccessoryCheckmark;
        }];
    }
}];

Add Default placeholder for image before loading it from url,As cells are being reused it takes the previous image

Answer 2

You can use SDWebImage.framework to load image

[cell.customImageView sd_setImageWithURL:[NSURL URLWithString:userDetails.userImageURL] placeholderImage:nil options:SDWebImageCacheMemoryOnly completed:^(UIImage *image, NSError *error, SDImageCacheType cacheType, NSURL *imageURL) {
      if (image) {
          [cell.customImageView setImage:image];
      }
}];

Answer 3

You can use Afnetworking class for this .

Simply import #import "UIImageView+AFNetworking.h"

And use this line:-

[cell.imgProfile setImageWithURL:imgurl placeholderImage:[UIImage imageNamed:@""]];

Imgurl is the image Url which you are getting from response