How to display alert dialog while connecting to server? - ios

Question

An async request has been sent to the server and here is my connection delegate.
in RKYLoginDelegate.m file, i made an alert to tell user that the member is verifying when receiving data.
didReceivedData
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
[_receivedData appendData:data];
loginAlertView = [[UIAlertView alloc] initWithTitle:#"message"
message:#"verifying member..."
delegate:self
cancelButtonTitle:nil
otherButtonTitles:nil];
[loginAlertView performSelectorOnMainThread:#selector(show) withObject:nil waitUntilDone:YES];
NSLog(#"Received data: %#", [[NSString alloc] initWithData:_receivedData encoding:NSUTF8StringEncoding]);
}
and in finish loading data, if nothing return, then shows the error message.
didFinishLoading
- (void)connectionDidFinishLoading:(NSURLConnection *)connection;
in the code, it will verify return state and parse value, if not respond then alert a dialog to notify user error message
if ([jsonDataDictionary count] > 0) {
// add member into data
RKYMemberManager *rkyMemberManager = [RKYMemberManager new];
[rkyMemberManager addMember:jsonDataDictionary];
// navigate to main
UIStoryboard *rkyMainStoryboard = [UIStoryboard storyboardWithName:#"RKYMainStoryboard" bundle:nil];
RKYMainViewController *rkyMainViewController =
[rkyMainStoryboard instantiateViewControllerWithIdentifier:#"RKYMain"];
[[[UIApplication sharedApplication] delegate].window.rootViewController.navigationController presentViewController:rkyMainViewController animated:YES completion:nil];
}
else {
UIAlertView *alertView = [[UIAlertView alloc]
initWithTitle:#"message"
message:#"Cannot login!"
delegate:self
cancelButtonTitle:#"OK"
otherButtonTitles:nil];
[alertView performSelectorOnMainThread:#selector(show) withObject:nil waitUntilDone:YES];
[alertView show];
NSLog(#"cannot login");
}
Those alert dialogs did show its message, but will cause an error:
Thread 1:EXC_BAD_ACCESS(code=2, address=0xc)
as title, am I doing correctly?
if yes, how to solve the problem that caused?