Question

I am trying to make Twitter work in my app and everything works fine except the code does not seem to recognize an error from Twitter. If the username/password are not valid, I get an error message through this function:

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data 
{
 NSString* strData = [[[NSString alloc] initWithBytes:[data bytes] length:[data length] encoding:NSASCIIStringEncoding] autorelease];
 NSLog(@"Received data: %@", strData ) ;
 return ;
}

It prints: Received data:

Could not authenticate you.
.

However, the app continues to the post a tweet view I have and ignores the error. Obviously, I do not have something setup right to detect such an error from twitter so my question is how do I get Xcode to recognize an error like this? This uses basic http auth btw and don’t mention anything about OAuth…just trying to get this to work for now.

    -(void) onLogin:(id)sender
    { 
 [loading1 startAnimating];

 NSString *postURL = @"http://twitter.com/account/verify_credentials.xml";
 NSMutableURLRequest *request = [ [ NSMutableURLRequest alloc ] initWithURL: [ NSURL URLWithString:postURL ] ];

 NSURLConnection *theConnection=[[NSURLConnection alloc] initWithRequest:request delegate:self];

 if (!theConnection) 
 {
  UIAlertView* aler = [[UIAlertView alloc] initWithTitle:@"Network Error" message:@"Failed to Connect to twitter" delegate:nil cancelButtonTitle:@"Close" otherButtonTitles:nil];
  [aler show];
  [aler release];
 } 

 else
 {
  receivedData = [[NSMutableData data] retain];
 }

 [request release];
    }

    -(void)connection:(NSURLConnection *)connection didReceiveAuthenticationChallenge:(NSURLAuthenticationChallenge *)challenge
    {
    if ([challenge previousFailureCount] == 0 && ![challenge proposedCredential]) 
 {
        NSURLCredential *newCredential;
        newCredential=[NSURLCredential credentialWithUser:txtUsername.text
                                                 password:txtPassword.text
                                              persistence:NSURLCredentialPersistenceNone];

        [[challenge sender] useCredential:newCredential forAuthenticationChallenge:challenge];
        } 
 else 
 {
  isAuthFailed = YES;
        [[challenge sender] cancelAuthenticationChallenge:challenge];
        }
    } 

Answer 1

ok so I can now get an error response or a authentication response in xml. now, how do I say, use this response as a triggering factor for connectionDidFailWithError because if twitter send me back an error, I want to give an in-app error.

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

NSXMLParser* parser = [[NSXMLParser alloc] initWithData:data];
[parser setDelegate:self];
[parser parse];

return;
}

- (void)parser:(NSXMLParser *)parser foundCharacters:(NSMutableString *)string
{
NSLog(@"response: %@", string);
}