using NSURLConnection instead of stringWithContentsOfURL - iphone

Question

Guys, I was retrieving an XML response from a .php script on my server using the following code:
NSString *xmlString = [NSString stringWithContentsOfURL:[NSURL URLWithString:urlString]
encoding:NSUTF8StringEncoding error:&error];
and
//tried also: if(error)
if(!xmlString)
{
NSString * errorString = [NSString stringWithFormat:#"Unable to download xml data (Error code %i )", [error code]];
UIAlertView * errorAlert = [[UIAlertView alloc] initWithTitle:#"Error loading content" message:errorString delegate:self cancelButtonTitle:#"OK" otherButtonTitles:nil];
[errorAlert show];
[errorAlert release];
}
//*** now I have a touchXML xPath query code that extracts what I need from XML
My .php script wasn't working today and my iApp was freezing without any alerts, errors or notifications? I thought that the code above will handle errors but it doesn't???
A) Then what type of error does it catch?
Then I remembered that i I should try working with NSURLConnection and its delegate methods to catch any error that occurs.
//Inside viewDidLoad method
NSMutableData *responseData = [[NSMutableData alloc] init];
NSURL *baseURL = [[NSURL URLWithString:self.chosenDrawRss] retain];
NSURLRequest *request = [NSURLRequest requestWithURL:baseURL];
[[[NSURLConnection alloc] initWithRequest:request delegate:self] autorelease];
NSString *xmlString = [[NSString alloc] initWithData:self.responseData encoding:NSUTF8StringEncoding];
The problem I had using this approach was that app ran the Connection in the background and continued executing the rest of the code found in viewDidLoad, so I had to reorganize my code a bit by moving it to another method that I call from delegate method connectionDidFinishLoading. The problem I have is that my delegate methods are not called. Well, all except didFailWithError: if I try to load URL that doesn't exist.
UPDATE:
delegate methods are called but it takes one minute or so for delegate method to be called and until alert message pops out...
B) Could I use stringWithContentsOfURL and still have an alert to the user if anything happens?
C) If not, then I need help with setting up NSURLConnection approach? I mean, what I'm missing here is why aren't my delegate methods called?
I truly hope my questions make sense :D
L

Answer 1

If your delegate method is called in didFailWithError then i suppose it will even be called in
connectionDidFinishLoading. Check by enabling a breakpoint in the delegate methods and track the flow. It may have happened the function returns before you call the delegate.
NSString *xmlString = [[NSString alloc] initWithData:self.responseData encoding:NSUTF8StringEncoding]
should be called in your delegate connectionDidFinishLoading method and in
- (void) connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
[responseData appendData:data];
}
I dont see why the alert should pop up after a minute unless you are doing some processing before displaying it.