Progress HUD is not shown before parsing XML

Question

I'm actually using the NSXMLParser class for parse an XML file hosted on a server. While the parser is doing his job I want to show a progress HUD grabbed there : https://github.com/jdg/MBProgressHUD

Here is how I show the Progress HUD :

MBProgressHUD *hud = [MBProgressHUD showHUDAddedTo:self.view animated:NO];
hud.labelText = @"Update"; 

Then I start the parser using a class I have made :

[dm parseXMLAtURL:[NSURL URLWithString:@"myXML.xml.php"]];

Here is the full class method :

- (void)parseXMLAtURL:(NSURL *)XMLUrl {
    NSXMLParser *parser = [[NSXMLParser alloc] initWithContentsOfURL:XMLUrl];
    [parser setDelegate:self];
    NSLog(@"start");
    [parser parse];    
}

I obviously call the MBProgressHUD before I parse the XML but there is no way : the MBProgressHUD is shown when the parser finish his job.

I think this problem could be due to the stack management, when he do the longest job before others (parsing the full XML takes like 6-7 secondes) Am I right or it could be another stuff? And if I'm right how can I manage this?

Answer 1

I can't say for sure from the code you have posted, but it could very well be because the XML parser is blocking your main thread.

To fix it, spawn of your XML parsing to anaother thread using dispatch_async or similar methods. This is also explained in the HUD Readme under Usage.

Regards