Is NSXMLParser's parse method asynchronous

Question

Is NSXMLParser's parse method asynchronous?

in other words if i have an NSXMLParse object and I call [someParseObject parse] from the main thread, will it block the main thread while it does its thing?

Answer 1

It is not asynchronous so it will block the main thread.

Answer 2

NSXMLParser can parse URL/Data, If we parse URL directly, it will freeze the UI(Main Thread),instead of that you can use Data Parsing by using NSXMLParser.Please go through NSURLConnection API for asynchronous fetching the data.

Answer 3

Yes it blocks. Here is how i have used NSInvocationQueue to not block the UI thread when parsing... just call beginParsing with the url path as a string and it will take care of the rest:

-(void) beginParsing:(NSString*) path{
    if(path ==nil)
        return;

    NSOperationQueue *queue = [[NSOperationQueue new] autorelease];

    NSInvocationOperation *operation= [[[NSInvocationOperation alloc]
                                             initWithTarget: self
                                                   selector: @selector(createRequestToGetData:)
                                                     object: path]
                                       autorelease];

    [queue addOperation:operation];
}

-(void)createRequestToGetData:(NSString*)path
{
    NSURL* Url = [NSURL URLWithString:path];

    NSXMLParser* parser = [[NSXMLParser alloc] initWithContentsOfURL:Url];

    [parser setDelegate:self];

    NSLog(@"path is %@",path);
    [parser parse];

    [path release];
    [parser release];
}

Answer 4

you can do like this NSXMLParser as asynchronous

dispatch_async( dispatch_get_global_queue(0, 0), ^{

    NSString * dovizUrl=@"http://www.tcmb.gov.tr/kurlar/today.xml";
    NSURL *url = [NSURL URLWithString:dovizUrl];
    NSXMLParser *xmlParser = [[NSXMLParser alloc] initWithContentsOfURL:url];
    xmlParser.delegate = self;
    // call the result handler block on the main queue (i.e. main thread)
    dispatch_async( dispatch_get_main_queue(), ^{
        // running synchronously on the main thread now -- call the handler
        [xmlParser parse];
    });
});