UIActivityIndicatorView freeze - iphone

Question

i have this function which call a function to check CMS for info. but the UIActivityIndicatorView freeze till the check is completed. not sure why.
EDIT: one thing funny, i commented out the performselector. the UIActivityIndicatorView still freezed. until i tapped my back button then it started to spin....
i'm using storyboard, iOS 5
-(void)showLoading
{
[activity startAnimating];
//loading is a label to show "File Loading"
loading.alpha =1;
//is a label to show a 0.3 alpha of the label
blackOverlay.hidden =0;
[self performSelector:#selector(updateFromInternet:) withObject:#"a" afterDelay:2];
//[self updateFromInternet:#"a"];
}
-(void)updateFromInternet:(NSString *)urlStr
{
NSString *URLString = #"http://sites.google.com/site/iphonesdktutorials/xml/Books.xml";
NSURL *updateDataURL = [NSURL URLWithString:URLString];
NSMutableURLRequest *WPXMLFetchRequest = [NSMutableURLRequest requestWithURL:updateDataURL];
self.receivedData = [NSMutableData data];
self.updateConnection = [NSURLConnection connectionWithRequest:WPXMLFetchRequest delegate:self];
NSLog(#"Checking update at : %#", updateDataURL);
//[self.updateConnection cancel];
}
-(void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
////NSlog(#"Receiving data");
[self.receivedData appendData:data];
}
-(void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
{
////NSlog(#"Failed to receive data");
self.receivedData = nil;
}
-(void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
////NSlog(#"Received response from data");
[self.receivedData setLength:0];
}
- (void)connectionDidFinishLoading:(NSURLConnection *)connection {
NSString *data=[[NSString alloc]initWithData:self.receivedData encoding:NSUTF8StringEncoding];
NSLog(#"data %#",data);
NSError *parseError = nil;
//NSDictionary *xmlDict = [XMLReader dictionaryForXMLData:self.receivedData error:&parseError];
self.receivedDict = [XMLReader dictionaryForXMLData:self.receivedData error:&parseError];
[self showDataOnScrollView];
}

Answer 1

You should delay the "heavy" function a bit and let the Activity Indicator fire.
try adding a 2.0 and not 2 to your delay (I would use a much smaller value - say 0.3)
[self performSelector:#selector(updateFromInternet:) withObject:#"a" afterDelay:0.3];
if this does not solve's your problem you should look (or post) the code related to the extra stuff you have in your code like : loading.alpha =1; and blackOverlay.hidden =0; which I assume are elements added to the Activity Indicator