NSUrlConnection Delegate methods are not getting called from helper class

I have to do SSL pinning so need to verify server side SSL certificate. SO I have to use NSURL delegates. I have a helper class in which I have created method which returns me login response:

- (NSData *)sendSynchronousRequest:(NSString *)strNewLoginRequest
             returningResponse:(NSURLResponse **)response
                         error:(NSError **)error {
NSMutableURLRequest *finalRequest = nil;

NSURL *url= [NSURL URLWithString:const_url];

finalRequest = [NSMutableURLRequest requestWithURL:url cachePolicy:NSURLRequestReloadIgnoringCacheData timeoutInterval:30.0];

NSData *requestData = [NSData dataWithBytes:[strLoginRequest UTF8String] length:[strLoginRequest length]];

    self.connection = [[NSURLConnection alloc] initWithRequest:finalRequest delegate:self startImmediately:NO];

    NSRunLoop *currentRunLoop = [NSRunLoop currentRunLoop];
    [self.connection unscheduleFromRunLoop:currentRunLoop forMode:NSDefaultRunLoopMode];
    [self.connection scheduleInRunLoop:currentRunLoop forMode:@"connectionRunLoopMode"];

    [self.connection start];

    while ([currentRunLoop runMode:@"connectionRunLoopMode" beforeDate:[NSDate distantFuture]]);

    return self.mutableResponse;
}

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
    self.response = response;
}

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
    self.mutableResponse = [[NSMutableData alloc]init];
    [self.mutableResponse appendData:data];

}

- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
{
    dispatch_async(dispatch_get_main_queue(), ^{

    if (loadingView)
    {
        [loadingView removeView];
    }

    UIAlertView *alert = [[UIAlertView alloc]initWithTitle:@"Failure" message:@"Network Failure" delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil, nil];

        [alert show];
    });
}

 - (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
    if (loadingView)
    {
        [loadingView removeView];
    }
    self.resultString = [[NSString alloc] initWithData:self.mutableResponse      encoding:NSASCIIStringEncoding];
}

and I am calling this method from another class called ViewController with code

-(void)doLogin
{
 self.service = [[SyncCommunicationService alloc]init];
 NSData *data = [self.service sendSynchronousRequest:strNewLoginRequest
                                  returningResponse:&response
                                              error:nil];
}

I have tried calling this method in background and on main thread but still delegate methods are not getting called, I have tried many other answers from same website but still couldn't able to solve this issue so please can anybody have a clue what am I doing wrong.

I'm wondering why would anyone use asynchronous request for performing task synchronously? Not to mention this strange way to wait with while statement instead of dispatch_semaphore or something similar.

However, why You even bother with delegate? Just use class method sendSynchronousRequest:returningResponse:error:. I think, it would suffice in your case