在后台下载数据的同时，从 JSON 中下载数据并存储到 CoreData 和 Display

Question

我在将数据显示到 tableview 的同时从 JSON 解析数据并存储到 CoreData 但我遇到的问题是数据仅在下载完成后才显示但我不想这样我想下载后台数据并在处理下载时显示数据我该怎么做呢

-(void)connectionDidFinishLoading:(NSURLConnection *)connection
{
    [UIApplication sharedApplication].networkActivityIndicatorVisible = NO;
    arrayData = [NSJSONSerialization JSONObjectWithData:data options:0 error:nil];
    NSError *error;
    NSManagedObjectContext *context = [appDelegate managedObjectContext];
    context = [appDelegate managedObjectContext];

    for (int i = 0; i < [arrayData count]; i++) {

        idNum = [arrayData objectAtIndex:i][@"id"];
        NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"Discount"];
        [request setPredicate:[NSPredicate predicateWithFormat:@"cID = %@",idNum]];
        [request setFetchLimit:1];
        NSUInteger count = [context countForFetchRequest:request error:&error];
        if (count == NSNotFound) {
            NSLog(@"ERROR");
        }else if (count == 0) {
            NSLog(@"New Data Coming");

            name  = [arrayData objectAtIndex:i][@"name"];
            summary = [arrayData objectAtIndex:i][@"summary"];
            region = [arrayData objectAtIndex:i][@"region"];
            imageURL = [arrayData objectAtIndex:i][@"images"][@"logo"];

            id  benefits1 = [arrayData objectAtIndex:i][@"benefits"];
            benefiteString = [NSString stringWithFormat:@"%@ %@",[benefits1 objectAtIndex:0][@"key"],[benefits1 objectAtIndex:0][@"value"]];
            NSData * data = [NSData dataWithContentsOfURL:[NSURL URLWithString:imageURL]];
            dateUpdate = [arrayData objectAtIndex:i][@"updated_at"];
            NSDateFormatter *dateFormatter = [[NSDateFormatter alloc]init];
            [dateFormatter setDateFormat: @"yyyy-MM-dd'T'HH:mm:ss.sssZ"];
            NSDate *date =[dateFormatter dateFromString:dateUpdate];
            [dateFormatter setDateFormat:@"yyyy/MM/dd HH:mm:ss"];
            NSLog(@"DAte : %@",date);
            Discount * d = [NSEntityDescription insertNewObjectForEntityForName:@"Discount" inManagedObjectContext:context];
            d.name = name;
            d.summary = summary;
            d.regions = region;
            d.cID = idNum;
            d.imageLogo = data;
            d.updated_at = date;
            d.benefits = benefiteString;
            if (![context save:&error]) {
                NSLog(@"Getting error while saving data");
            }
            else{
                NSLog(@"Saved");
            }
        }

    }
    [sharedAppDelegate dismissGlobalHUD];
    [listTableView reloadData];
}

-(NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    return [_myArray count];
}
-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    customCellClass = [tableView dequeueReusableCellWithIdentifier:@"Cell"];
    if (customCellClass == nil)
    {
        customCellClass = [[CellCustom alloc]initWithStyle:UITableViewCellStyleDefault reuseIdentifier:@"Cell"];
    }
    customCellClass.nameLabel.text = [[_myArray objectAtIndex:indexPath.row]name];
    customCellClass.cityLabel.text =[[_myArray objectAtIndex:indexPath.row]regions];
    customCellClass.detailLabel.text = [[_myArray objectAtIndex:indexPath.row]summary];

    NSData * d = [[_myArray objectAtIndex:indexPath.row]imageLogo];
    customCellClass.mainImage.image = [UIImage imageWithData:d];

    customCellClass.benefitsLabel.text = [[_myArray objectAtIndex:indexPath.row]benefits];
    [sharedAppDelegate dismissGlobalHUD];
    return customCellClass;
}

-(void)dataDidSave
{

    NSManagedObjectContext *context = [appDelegate managedObjectContext];
    NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
    NSEntityDescription *entity = [NSEntityDescription entityForName:@"Discount" inManagedObjectContext:context]; [fetchRequest setEntity:entity];
    [fetchRequest setEntity:entity];
    NSError *error = nil;
    NSArray *result = [context executeFetchRequest:fetchRequest error:&error];

    self.myArray = result;
    [listTableView reloadData];
}
-(void)viewWillAppear:(BOOL)animated
{
    [sharedAppDelegate showGlobalProgressHUDWithTitle:@"Loading..."];
    [self dataDidSave];
}

Answer 1

在 connectionDidFinishLoading 中：尝试这样的事情：

dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT,0),^ {
   // Process your data and then incrementally call 
      dispatch_async(dispatch_get_main_queue(),^ {
           [listTableView reloadData];
      });
    }
});