在重新加载UITableView数据后，indexPathForCell返回null

Question

我在ViewController中有一个UITableView，它包含一个自定义单元格。当视图第一次加载时，下面代码中的indexPathForCell返回indexPath，没有问题:

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    PostCell *postCell = (PostCell *)[tableView dequeueReusableCellWithIdentifier:@"PostCell"];
    if (postCell == nil) {
        NSLog(@"EmptyCell Found");
    }
    NSDictionary *object = [postArray objectAtIndex:indexPath.row];
    NSString *imageURL = [object objectForKey:@"imageURL"];
    NSIndexPath *originalIndexPath = indexPath;
    NSLog(@"Original IndexPath %@", originalIndexPath);
    SDWebImageManager *manager = [SDWebImageManager sharedManager];
        [manager downloadWithURL:[NSURL URLWithString:imageURL]
                         options:indexPath.row == 0 ? SDWebImageRefreshCached : 0
                        progress:^(NSInteger receivedSize, NSInteger expectedSize){}
                       completed:^(UIImage *image, NSError *error, SDImageCacheType cacheType, BOOL finished){
                           if (image) {
                               // This returns correctly on first load
                               NSIndexPath *currentIndexPath = [imageTableView indexPathForCell:postCell];
                               NSLog(@"Current IndexPath %@", currentIndexPath);
                           }
                       }
        ];
}

刷新tableView后，currentIndexPath总是(null)。我的刷新代码如下:

- (void)refreshMainView {
    AFHTTPRequestOperation *downloadPostOperation = [[AFHTTPRequestOperation alloc] initWithRequest:serviceRequest];
    [downloadPostOperation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) {
        //[tableView beginUpdates];
        NSDictionary *json = [NSJSONSerialization JSONObjectWithData:urlData options:kNilOptions error:&error];
        NSMutableArray *newPostArray = [json objectForKey:@"posts"];
        // Replacing the old array with new array
        postArray = newPostArray;    
        [self stopRefresh];        
        //[tableView endUpdates]
        [imageTableView reloadData];
    } failure:^(AFHTTPRequestOperation *operation, NSError *error) {
        [self stopRefresh];
    }];

如果我只是执行[tableView reloadData]而不执行refreshMainView，那么获取currentIndexPath不会有任何问题。

一定是我忽略了什么，有人能帮帮我吗?谢谢你！

编辑:我已经尝试了[postCell.postImageView setImageWithURL:[NSURL URLWithString:imageURL] placeholderImage:nil];而不是刷新工作，所以我怀疑我在完成块中获得indexPath有问题，请问有人能帮忙吗?我需要完整的块，因为我正在做一些图像处理。

Answer 1

你好，我终于修好了。

对于需要答案的人，只需添加

dispatch_async(dispatch_get_main_queue(), ^{});

Answer 2

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    PostCell *postCell = (PostCell *)[tableView dequeueReusableCellWithIdentifier:@"PostCell"];

    if (cell == nil)
        {
                nib = [[NSBundle mainBundle] loadNibNamed:@"PostCell" owner:self options:nil];
}
    NSIndexPath *originalIndexPath = indexPath;
    NSLog(@"Original IndexPath %@", originalIndexPath);
SDWebImageManager *manager = [SDWebImageManager sharedManager];
    [manager downloadWithURL:[NSURL URLWithString:imageURL]
                     options:indexPath.row == 0 ? SDWebImageRefreshCached : 0
                    progress:^(NSInteger receivedSize, NSInteger expectedSize){}
                   completed:^(UIImage *image, NSError *error, SDImageCacheType cacheType, BOOL finished){
                       if (image) {
                           // This returns correctly on first load
                           NSIndexPath *currentIndexPath = [imageTableView indexPathForCell:postCell];
                           NSLog(@"Current IndexPath %@", currentIndexPath);
                       }
                   }
    ];

使用这个，它可能会帮助你