Image not loading immediately in Table View

Question

I'm using SDWebImage and grabbing Images associated with a news article from a news API.

The problem is, the images for the cells on screen aren't loading until I start scrolling on the UITableView. Once I scroll past a cell, and it goes off screen, once I come back to it the Image will finally be loaded.

Here is my (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath code:

if ([feedLocal.images count] == 0) {
    [cell.imageView setImage:[UIImage imageNamed:@"e.png"]];
}
else {    
    Images *imageLocal = [feedLocal.images objectAtIndex:0];
    NSString *imageURL = [NSString stringWithFormat:@"%@", imageLocal.url];
    NSLog(@"img url: %@", imageURL);

    // Here we use the new provided setImageWithURL: method to load the web image
    __weak UITableViewCell *wcell = cell;
    [cell.imageView setImageWithURL:[NSURL URLWithString:[NSString stringWithFormat:@"%@", imageURL]]
                   placeholderImage:[UIImage imageNamed:@"115_64.png"]
                          completed:^(UIImage *image, NSError *error, SDImageCacheType cacheType) {
                              if(image == nil) {
                                  [wcell.imageView setImage:[UIImage imageNamed:@"115_64.png"]];
                                   //];
                              }
                          }
    ];
}

Any idea why this would be happening? It just seems like when the UITableView loads, the Images aren't being told to load or something until scrolling begins?

Any suggestion is much appreciated, thanks!

Answer 1

There is little chance this will solve your problem, but this is too long to fit in a comment:

Tip 1:

If you are reusing cells, you should not do [wcell.imageView setImage:] in the callback. At the time the callback code is executed, there a non-null chance that wcell will point to a different cell in the table view than the one you wanted to change the image.

Instead, use the indexPath to refer to the cell you wanted to modify:

completed:^(UIImage *image, NSError *error, SDImageCacheType cacheType) {
    if(image == nil) {
        UITableViewCell *actualCell = [tableView cellForRowAtIndexPath:indexPath];
        [actualCell.imageView setImage:[UIImage imageNamed:@"115_64.png"]];
    }
}

Note that if the cell you wanted to change the image is not shown anymore, cellForRowAtIndexPath: will return nil, which is absolutely fine:

Return Value

An object representing a cell of the table or nil if the cell is not visible or indexPath is out of range.

Tip 2:

There is no need to re-create a string when you already have one ;)

[NSURL URLWithString:[NSString stringWithFormat:@"%@", imageURL]]

[NSURL URLWithString:imageURL] // imageURL is already a string

Your problem:

I'm a little bit puzzled, the code you showed really is a simple application of SDWebImage "how-to" examples, and I just tested with the v3.3 of the framework, and my cells update just fine. So try to reduce your code to the bare minimum to identify the real issue.

I'd say get rid of all your application logic (the feedLocal.images for example), and just find out if the problem actually comes from SDWebImage or not.