delegate methods are not called and parse property is always FALSE

Question

I am trying to parse an xml feed on the app delegate didFinishLaunchingWithOptions: method:

//Parse XML Data
    NSXMLParser *xmlParser = [[NSXMLParser alloc] initWithContentsOfURL:[NSURL URLWithString:@"http://xxxxxxxxxxxxxxxxx/xml"]];//url is just fine :)
    [xmlParser setDelegate:self];
    BOOL parseState = [xmlParser parse];
    if (parseState) {
        NSLog(@"parse succeeded");
    }else{
        NSLog(@"parse failed");//Always parse failed, parse is always "NO"
    }

Delegate protocol methods (none is called):

#pragma mark - NSXMLParserDelegate

- (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qualifiedName attributes:(NSDictionary *)attributeDict{
    NSLog(@"parser:didStartElement:namespaceURI:qualifiedName:attributes:");

}

- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string{

    NSLog(@"parser:foundCharacters:");
}
- (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName{
    NSLog(@"parser:didEndElement:namespaceURI:qualifiedName:");


}

And of course, AppDelegate.h conforms to the NSXMLParserDelegate protocol:

@interface AppDelegate : UIResponder <UIApplicationDelegate,NSXMLParserDelegate>

What am I missing? why protocol methods are not called and why [xmlParser parse] always return NO? Thanx.

Implement the `parser:parseErrorOccurred:` delegate method and see what the error is. — rmaddy, Jul 20 '13 at 02:08
Hi rmaddy, I used that delegate method, the parameter `parseError`'s code is `5` and the dictionary is just empty. — Malloc, Jul 20 '13 at 02:42
Are you 100% certain the XML document is well-formed? An error code 5 while parsing XML is `NSXMLParserPrematureDocumentEndError`. Can you create an `NSURLConnection` to download the file from the same URL using `sendSynchronousRequest:`, and print the response to the console? — Craig Otis, Jul 20 '13 at 03:09

Dan · Answer 1 · 2013-07-20T03:02:36.010

Is there a reason you're cramming your XML parser inside the AppDelegate? Without exception I've found it to be beneficial to always instantiate a parser class to handle parsing tasks. For example...

myParser.h

@class parseClass;

@interface myXMLParser : NSObject <NSXMLParserDelegate> {

}

- (myXMLParser *) initmyXMLParser;

myParser.m

//I do my instantiating like this so it can only be done once
//If you need to instantiate the class more than once do NOT use dispatch_once!
- (myXMLParser *)initmyXMLParser
{
    static myXMLParser *newInstance = nil;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        newInstance = [[myXMLParser alloc]init];
    });
    return newInstance;
}
//include other delegate methods as well

AppDelegate.m

#import "myParser.h"

NSXMLParser *xmlParser = [[NSXMLParser alloc] initWithContentsOfURL:[NSURL      URLWithString:@"http://xxxxxxxxxxxxxxxxx/xml"]];//url is just fine :)
myXMLParser *theParser = [[myXMLParser alloc]initmyUpdateXMLParser];
[xmlParser setDelegate:theParser];
BOOL parseState = [xmlParser parse];
if (parseState) {
    NSLog(@"parse succeeded");
}else{
    NSLog(@"parse failed");//Always parse failed, parse is always "NO"
}

That code is stripped down and refactored from a project I have open right now... and meshed with your example above. So, yes, the basis & logic behind the code works. Did I create a typo somewhere doing this from the hip? Possibly. — Dan, Jul 20 '13 at 02:40

score 0 · Accepted Answer · answered Jul 20 '13 at 03:26

0

Might it be an ARC error, try setting up xmlparser as a strong property so that it won't be deallocated before finishing parsing the file.

You may want to download the xml from the web before parsing it using an nsurlconnection

answered Jul 20 '13 at 03:26

Blevz

30
5

I bet about it before going to sleep yesterday and first thing I tried when I wake up this morning. That was exactly the problem, I had to make the `NSXMLParser`a strong property (`retain` for pre-ARC terminology). – Malloc Jul 20 '13 at 07:24

delegate methods are not called and parse property is always FALSE

2 Answers2