Traditional.m

-(IBAction)didPressConnectButton:(id)sender {
    NSURL *url = [NSURL URLWithString:@"http://someurl.com/api?parameter"];
    NSURLRequest *request = [[NSURLRequest alloc] initWithURL:url];
    self.connection1 = [[NSURLConnection alloc] initWithRequest:request delegate:self];
}

#pragma mark - NSURLConnectionDataDelegate Methods

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response {
    self.responseData = [[NSMutableData alloc] init];
}

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {
   [self.responseData appendData:data];

}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection {
    if ([connection isEqual: self.connection1]) {
        NSData *data = self.responseData;
        //Do something with the data
    }
}

#pragma mark - NSURLConnectionDelegate Methods

- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error {
    //Handle error scenario
}