reload tableView in last method run

Question

I have method that get notification as I download one image. I can download a lot of objects and I want to update tableView then I have last notification of downloaded image. How the best way to accomplish it?

- (void)requestDownloadAvatarWithImageString:(NSString *)imageString completion:(void (^)(AFHTTPRequestOperation *operation, UIImage *image, NSError *error))completion __attribute__((nonnull(2)))
{
NSParameterAssert(completion);

NSString *urlString = imageString;
NSURL *url = [NSURL URLWithString:urlString];
NSURLRequest *urlRequest = [NSURLRequest requestWithURL:url];

AFHTTPRequestOperation *requestOperation = [[AFHTTPRequestOperation alloc] initWithRequest:urlRequest];
requestOperation.responseSerializer = [AFImageResponseSerializer serializer];

[requestOperation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) {

    completion(operation, responseObject, nil);

} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
    DDLogError(@"FAIL download image: %@",error);
}];

[requestOperation start];
}

@ nhgrif , I need to call only with last notification. For ex[ample in 5 sec I have 100 notifications, I need last — user3587674, May 03 '14 at 20:00
Then keep track of how many you're waiting for. Better would probably be to reload the cell for which the download just completed (reload an individual cell) — nhgrif, May 03 '14 at 20:03
How then I can detect that I will have notification rather then it was last? — user3587674, May 03 '14 at 20:05
By including a lot more code. There's a million different ways. — nhgrif, May 03 '14 at 20:06

zontragon · Accepted Answer · 2014-05-03T21:04:28.880

0

dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);

dispatch_semaphore_t semaphore = dispatch_semaphore_create(NUMBER_OF_RETURNED_OBJECTS);
dispatch_async(queue, ^{
    for (i = 0; i<NUMBER_OF_RETURNED_OBJECTS; i++)
    {
        dispatch_async(queue, ^{

            fetchObject(i); // it's specific to your application

            dispatch_semaphore_signal(semaphore);
        }
    }
    dispatch_semaphore_wait(semaphore, DISPATCH_TIME_FOREVER);
}   

[your_table_view reloadData];

or simply get all image paths in an array then download them with SDWebImage

- (UITableViewCell *) tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{

UITableViewCell *cell = [self.tableView dequeueReusableCellWithIdentifier:MyIdentifier];


NSString *url = [NSString stringWithString, imageArray[indexPath.row]];

[cell.cell_image setImageWithURL:[NSURL URLWithString: url] placeholderImage:[UIImage imageNamed:@"placeholder.png"]];

}

edited May 03 '14 at 21:04

answered May 03 '14 at 20:17

zontragon

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make all downloads asynchronously. – zontragon May 03 '14 at 20:29
make all download asynchronously. dispatch_semaphore_wait waits until all of them finished – zontragon May 03 '14 at 20:30
I need to run it from download method in complete block? if I do not know NUMBER_OF_RETURNED_OBJECTS how nan I work with it? – user3587674 May 03 '14 at 20:33
How do you download them? Could you send some piece of code? – zontragon May 03 '14 at 20:36
I would download image paths as an array and place them to table. Then I would load the images with SDWebImage in TableView's data source method. – zontragon May 03 '14 at 20:41
I added download method in my post – user3587674 May 03 '14 at 20:41
is imageString belong only one image? – zontragon May 03 '14 at 20:43
Yes. I use this method to download images for parts of app. Basically I want to reload tableView then I received last notification of downloaded image – user3587674 May 03 '14 at 20:43
Does this function only return one image? – zontragon May 03 '14 at 20:45
Yes, it did, responseObject is one image – user3587674 May 03 '14 at 20:45
How do you know how many photos should you fetch? – zontragon May 03 '14 at 20:47
I parse web response and have as much images as links it have – user3587674 May 03 '14 at 20:49
If you already know the number of photos you should know the which one is the last one. – zontragon May 03 '14 at 20:49
I do not know number of photos. – user3587674 May 03 '14 at 20:50
You said "I parse web response and have as much images as links it have " so you know the image links. Add them all to an array then load them with SDWebImage in tableView:cellForRowAtIndexPath method. – zontragon May 03 '14 at 20:54
[cell.cell_image setImageWithURL:[NSURL URLWithString: url] placeholderImage:[UIImage imageNamed:@"placeholder.png"]]; – zontragon May 03 '14 at 20:55
NO no no, I can not do it my data model. I solve it. I add NSInteger in download class and increase it then I have download and decrease it then it finished. Then check for this number. IF it 0 - I reload tableView – user3587674 May 03 '14 at 21:32

reload tableView in last method run

1 Answers1