Question

I am working on a project in which at first web service call we are getting some 20 number of data which we are loading to table view and once we start scrolling up for view when it reaches 20 number we need to call service for next 20 no’s, like facebook does.

This we need to do for each next 20 until data ends and load to tableview from last data of previous call and we can see all data when we scroll down for previous data. And need to show “more data loading” when we scroll up table after 20th cell.

Please Help me !

Thanks,

Answer 1

Simply create private offset variable and increase it each time on success loading.

Let’s think this is your web service that gets GET parameters:

http://server.com/?offset=0&amount=20

Your Objective C code will look like this:

In header file:

@interface YourClass
{
   uint _offset;
}
@end

In implementation file:

- (void)viewDidLoad {
    _offset = 0;
}

- (void)loadFromServer {
    NSString *stringURL = [NSString stringWithFormat:@"%@/%@", kServer, _offset];
    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:stringURL]];
    NSString *params = [NSString stringWithFormat:@"offset=%i&amount=20", _offset];
    NSData *postData = [params dataUsingEncoding:NSUTF8StringEncoding];

    request.HTTPMethod = @"GET";
    request.HTTPBody = postData;

    [NSURLConnection sendAsynchronousRequest:request queue:[NSOperationQueue mainQueue] completionHandler:^(NSURLResponse *response, NSData *data, NSError *error) {

    if (error) {
        NSLog(@"Error: %@", error);
    }else {
        NSError *jsonError;
        NSDictionary *json = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableLeaves error:&jsonError];

        _offset += 20;
    }
}];

}