问从用于循环的服务器中获取数据的iOS

EN

NSInteger count = [[feed objectForKey:@"content"] count];
NSMutableArray *dataSourceArray = [NSMutableArray arrayWithCapacity:count];

for (NSInteger i = 0; i < count; ++i) {
    [dataSourceArray addObject:[NSNull null]];
}

__block NSError *apiCallError = nil; // Just to keep track if there was at least one API call error
NSInteger index = 0;

// Create the dispatch group
dispatch_group_t serviceGroup = dispatch_group_create();

for (NSDictionary *feedItem in [feed objectForKey:@"content"]) {

    // Start a new service call
    dispatch_group_enter(serviceGroup);

    // url with feedItem data.
    NSURL *url = ...

    [UrlMethod GetURL:url success:^(NSDictionary *placeData) {
        if (placeData) {
            dispatch_async(dispatch_get_main_queue(), ^{
                // Add data to Data Source
                // index should be the correct one, as the completion block will contain a snapshot of the corresponding value of index
                dataSourceArray[index] = [placeData objectForKey:@"data"];
            }

            dispatch_group_leave(serviceGroup);
       } failure:^(NSError *error) {
           apiCallError = error;
           dispatch_group_leave(serviceGroup);
       }];

     index++; 
}

dispatch_group_notify(serviceGroup, dispatch_get_main_queue(),^{
    if (apiCallError) {
        // Make sure the Data Source contains no [NSNull null] anymore
        [dataSourceArray removeObjectIdenticalTo:[NSNull null]];
    }

    // Reload Table View
    [self.tableView reloadData];
});

 //keep dictionary property which will store responses
    NSMutableDictionary *storeResponses = [[NSMutableDictionary alloc]init];

    //Somewhere outside function keep count or for loop
    NSInteger count = 0;

    for (NSDictionary *feedItem in [feed objectForKey:@"content"]) {
        //Find out index of feddItem
        NSInteger indexOfFeedItem = [[feed objectForKey:@"content"] indexOfObject:feedItem];

        NSString *keyToStoreResponse = [NSString stringWithFormat:@"%d",indexOfFeedItem];

        // url with feedItem data.
        NSURL *url = ....
        [UrlMethod GetURL:url success:^(NSDictionary *placeData) {
            if (placeData) {
                //instead of storing directly to array like below
                // adding object to table data source array
                [dataSourceArray addObject:[placeData objectForKey:@"data"]];

                //follow this
                //increase count
                count++;
                [storeResponses setObject:[placeData objectForKey:@"data"] forKey:keyToStoreResponse];


                // reloading table view.
                if(count == [feed objectForKey:@"content"].count)
                {
                    NSMutableArray *keys = [[storeResponses allKeys] mutableCopy]; //or AllKeys
                    //sort this array using sort descriptor
                    //after sorting "keys"

                    for (NSString *key in keys)
                    {
                        //add them serially

                        [dataSourceArray addObject:[storeResponses objectForKey:key]];
                    }

                    dispatch_async(dispatch_get_main_queue(), ^{


                        [self.tableView reloadData];



                    });
                }

            }
        } failure:^(NSError *error) {

        }];
    }