Question

I have a file:

<xml>
    <component>something
        <system>somethingDeeper
            <value>somethingDeepest</value>
        </system>
    </component>

    <component>somethinfDifferent
        <value>somethingDifferentDeeper</value>
    </component>

    <value>somethingNew</value>
</xml>

So I want to distinguish what is inside another tag (ex. <system>) what is not. How to do this with NSXMLParser? I currently use BOOL ivar’s but this is a lot of tags and this is not as elegant as I want it to be. I know that NSXMLParser is a SAX parser and I understand that.

In above example I will be enter to didEndElement method three times with:
elementName equal value Is there a more elegant way to distinguish what entry was from <component> tag above what not?

Answer 1

You could keep an array of tag names you are currently within

NSMutableArray *tagNameStack;

Each time you enter a new element you add it to this array. Each time you leave you remove it again. i.e.

- (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qualifiedName attributes:(NSDictionary *)attributeDict {
    [tagNameStack addObject:elementName];

    // Your code here
}

and

- (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName {
    // Your code here

    [tagNameStack removeLastObject];
}

So, when you are parsing somethingDeepest your tagNameStack array would be

@"xml", @"component", @"system", @"value"

You can use this stack to decide where you are in the xml i.e.

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

    if ([tagNameStack containsObject:@"system"]) {
        // Deal with the value inside the system tag
    } else if ([tagNameStack containsObject:@"component"]) {
        // Deal with the value inside the component tag
    } else {
        // This must be the value inside the XML tag
    }
}