iphone using NSXML parser how to parse the attributes

Question

I want to know how to parse the attributes in below xml file

<ROOT_ELEMENT><RESPONSE READ_TAG="LEVEL_LIST" RESULT="" TEXT=""/><USER USER_NAME="newadmin01" TOKEN_ID="0.766003221016982" FULL_NAME="newadmin01, newadmin01"/><DATETIME UNFORMATTED_TEXT="Aug 10 2011 12:25PM" FORMATTED_TEXT="10 Aug 12:25"/><BREADCRUMB/><LEVEL_LIST><LEVEL ID="4519" NAME="Mega Mart" CHILD_EXISTS="Y" ADD_EDIT_PRIVILEGE="Y"/></LEVEL_LIST></ROOT_ELEMENT>

here it is my parser code

- (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary *)attributeDict {
    elemName = [[NSString alloc] initWithString:elementName];
    NSLog(@"element Name = %@", elementName);
}

- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string {   
    if ([elemName isEqualToString:@"RESPONSE"]) {
        if (!currentValueString) {
            currentValueString = [[NSMutableString alloc] initWithCapacity:1024];
        }
        [currentValueString appendString:string];
    }
    else if ([elemName isEqualToString:@"USER"]) {
        if (!currentValueString) {
            currentValueString = [[NSMutableString alloc] initWithCapacity:1024];
        }
        [currentValueString appendString:string];
    }
    if ([elemName isEqualToString:@"DATETIME"]) {
        if (!currentValueString) {
            currentValueString = [[NSMutableString alloc] initWithCapacity:1024];
        }
        [currentValueString appendString:string];
    }
    else if ([elemName isEqualToString:@"BREADCRUMB"]) {
        if (!currentValueString) {
            currentValueString = [[NSMutableString alloc] initWithCapacity:1024];
        }
        [currentValueString appendString:string];
    }
    else if ([elemName isEqualToString:@"LEVEL"]) {
        if (!currentValueString) {
            currentValueString = [[NSMutableString alloc] initWithCapacity:1024];
        }
        [currentValueString appendString:string];
    }

}

- (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName {
    if ([elemName isEqualToString:@"RESPONSE"]) {
        [tableDataArray addObject:currentValueString];

        [currentValueString release];
        currentValueString = nil;

        [elemName release];
        elemName = nil;

    }   
    else if ([elemName isEqualToString:@"USER"]) {
        [tableDataArray addObject:currentValueString];

        [currentValueString release];
        currentValueString = nil;

        [elemName release];
        elemName = nil;

    }   
    else if ([elemName isEqualToString:@"DATETIME"]) {
        [tableDataArray addObject:currentValueString];

        [currentValueString release];
        currentValueString = nil;

        [elemName release];
        elemName = nil;

    }   
    else if ([elemName isEqualToString:@"BREADCRUMB"]) {
        [tableDataArray addObject:currentValueString];

        [currentValueString release];
        currentValueString = nil;

        [elemName release];
        elemName = nil;

    }   
    else if ([elemName isEqualToString:@"LEVEL"]) {
        [tableDataArray addObject:currentValueString];

        [currentValueString release];
        currentValueString = nil;

        [elemName release];
        elemName = nil;
    }   

}

Answer 1

Look at the NSXMLParserDelegate's message declaration

- (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qualifiedName attributes:(NSDictionary *)attributeDict

It has an attributeDict for the element you currently parse.

Iterate over the key-value pairs and deal with them as you like.

- (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary *)attributeDict {
    elemName = [[NSString alloc] initWithString:elementName];
    NSLog(@"element Name = %@", elementName);
    NSEnumerator *keyEnumerator = attributeDict.keyEnumerator()


    // for each element the parser encounters:
    // create a new dictionary to hold the attributes
    NSMutableDictionary *myAttributes = [[NSMutableDictionary alloc] init];

    // go through each attribute for the elementName tag
    while ( (id aKey = [keyEnumerator nextObject]) )
         // and store the attribute to the dictionary by copying over the values
         [myAttributes setObject:[attributesDict objectForKey:aKey] forKey:aKey];

    // after we caught all attributes and copied them into our own data structure
    // put them into an instance dicionary to get a structure which holds 
    // all attributes for any element tag we encounter 
    // accessible by the elementName as key
    [self.attributesByElementDictionary setObject:myAttributes forKey:elementName];
    [myAttributes release];
}

Practically this would produce a dictionary for the - example: - RESPONSE tag: The dictionary would look like:

{
    "READ_TAG": "LEVEL_LIST",
    "RESULT": "",
    "TEXT": ""
}

For a more general solution you would not use a flat dictionary but rather form some kind of tree structure. This is a little bit more work and more robust - but this little example should give you the idea to extract the attributes from a tag and process them afterwards