Question

I have an xml file with a parent child structure such as :

<geometry id="001-mesh" name="001">
  <mesh>
    <source id="001-mesh-positions">
      <float_array id="001-mesh-positions-array" count="228">

I am able to parse the data successfully using NSXMLParser. However the problem is I want to store the child information in relation to the parent – for example when a geometry id is detected, I then want to store the associated source id and float_array id.

Can anyone suggest a way I could this ? The below code will detect when a given element is found during parsing, but I’m not sure how to then store the values.

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

// NSLog(@"Parse Started");
//NSLog(@"Element Name is %@", elementName);

if([elementName isEqualToString:@"geometry"]) { 
    NSLog(@"Object Detected");
    NSString *name = [attributeDict objectForKey:@"name"];

NSLog(@"Name is %@",name);
}

if ([elementName isEqualToString:@"float_array"]) {
    NSLog(@"Vertices Detected");
    NSString * vertices = [attributeDict objectForKey:@"count"];

    NSLog(@"Vertices are %@", vertices);
}

}

Answer 1

At the time when the parser detects the geometry tag, the source id and float_array id are not available: they have not been parsed yet. The usual trick is to wait for the child element, and do the processing when it becomes available. You can do it by creating a new Geometry object (or whatever corresponds to XML’s geometry tag in your model), and make it available to the didStartElement:...: method, for example by setting it into an ivar called myGeometry. Once you detect float_array element, parse its id, and call

[myGeometry setId:floatArrayId];