Parsing XML with a lot of children nodes to UITableView - iphone

Question

I have an xml file that looks like this:
<result>
<trip duration="03:30">
<takeoff date="2010-06-19" time="18:40" city="Moscow"/>
<landing date="2010-06-19" time="20:10" city="Novgorod"/>
<flight carrier="Rossiya" number="8395" eq="320"/>
<price>13429.00</price>
</trip>
<trip duration="03:40">
<takeoff date="2010-06-19" time="09:20" city="Omsk"/>
<landing date="2010-06-19" time="11:15" city="Paris"/>
<flight carrier="AirFrance" number="1145" eq="320"/>
<price>13229.00</price>
</trip>
<trip duration="03:50">
<takeoff date="2010-06-19" time="07:20" city="Omsk"/>
<landing date="2010-06-19" time="14:15" city="Barcelona"/>
<flight carrier="AirFrance" number="1100" eq="320"/>
<price>13329.00</price>
</trip>
</result>
I'd like to get all the parameters and place them in 3 UITableViewCells. As you can see there are 3 flights and the data about them.
I've been trying to parse it in a TableView but I only managed to get the <price> thing going.
How would you deal with parsing complex-structured parameters within an XML file? I mean how would I get takeoff date parameter and so on and so forth?
As far as I could get you can't apply the tactics I'm using like this one:
- (void) parser:(NSXMLParser *)parser didEndElement:(NSString *)elementname namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName
{
if ([elementname isEqualToString:#"price"])
{
currentTweet.dateCreated = currentNodeContent;
}
Any help would be highly appreciated. Thanks in advance.

Answer 1

This is the code that I frequently use to build a dictionary from an XML file that follows this basic model of some well defined repeating element (in this case, "trip"), and a series of data elements within that, some of which I'm reading the attributes of the tag (in this case, "takeoff", "landing" and "flight"), and others I'm reading the data between the opening and closing tags (in this case, just "price").
I have the following ivars:
#interface XmlParserViewController () <NSXMLParserDelegate>
{
NSMutableArray *trips;
NSMutableDictionary *currentTrip;
NSMutableString *currentElement;
}
#end
And then the code looks like:
- (void)viewDidLoad
{
[super viewDidLoad];
trips = [[NSMutableArray alloc] init];
// I'm getting my xml from my bundle. You get it however you're currently getting it.
NSString *filename = [[NSBundle mainBundle] pathForResource:#"results" ofType:#"xml"];
NSData *data = [NSData dataWithContentsOfFile:filename];
NSXMLParser *parser = [[NSXMLParser alloc] initWithData:data];
parser.delegate = self;
[parser parse];
}
#pragma mark - NSXMLParserDelegate methods
#define kRowElementTag #"trip"
- (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qualifiedName attributes:(NSDictionary *)attributeDict
{
NSArray *attributeElementNames = #[#"takeoff", #"landing", #"flight"];
NSArray *foundCharacterElementNames = #[#"price"];
if ([elementName isEqualToString:kRowElementTag])
{
currentTrip = [[NSMutableDictionary alloc] init];
[trips addObject:currentTrip];
if (attributeDict)
[currentTrip setObject:attributeDict forKey:elementName];
}
else if (currentTrip)
{
if ([attributeElementNames containsObject:elementName])
{
if (attributeDict)
[currentTrip setObject:attributeDict forKey:elementName];
}
else if ([foundCharacterElementNames containsObject:elementName] && currentElement == nil)
{
// you can change this to just grab a few fields ... add whatever fields you want to this
currentElement = [[NSMutableString alloc] init];
[currentTrip setObject:currentElement forKey:elementName];
}
}
}
- (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName
{
if ([elementName isEqualToString:kRowElementTag])
{
currentTrip = nil;
}
else if (currentElement)
{
currentElement = nil;
}
}
- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string
{
if (currentElement)
{
[currentElement appendString:string];
}
}
- (void)parser:(NSXMLParser *)parser parseErrorOccurred:(NSError *)parseError
{
NSLog(#"%s error=%#", __FUNCTION__, parseError);
// we should handle the error here
}
- (void)parserDidEndDocument:(NSXMLParser *)parser
{
NSLog(#"%s trips=%#", __FUNCTION__, trips);
// generally I immediately kick off the reload of the table, but maybe
// you want to grok the trips dictionary first.
//
// [self.tableView reloadData];
}
As you can guess, I'm trying to end up with that sort of nested array/dictionary structure that we've gotten used to parsing JSON files. Clearly, I don't like the fact that I have to identify some of the structure of the XML file up front in my code (the fact that the outer array has "trip" tags, that "takeoff", "landing", and "flight" have attributes but "price"` doesn't), etc. But this is a little better than my first attempts at XML parsing that hardcoded values all over the place. Sigh.

Answer 2

You have to manage didStartElement too. This is a sample metacode could be good for you:
-(void)parser:(NSXMLParser*)parser didStartElement:(NSString *)elementName namespaceURI:(NSString*)namespaceURI qualifiedName:(NSString*)qualifiedName attributes:(NSDictionary*)attributeDict {
if([elementName isEqualToString:#"trip"]) {
currentTweet.tripDuration = [attributeDict objectForKey:#"duration"];
} else if ([elementName isEqualToString:#"takeoff"]) {
currentTweet.takeoffDate = [attributeDict objectForKey:#"date"];
currentTweet.takeoffTime = [attributeDict objectForKey:#"time"];
currentTweet.takeoffCity = [attributeDict objectForKey:#"city"];
} else if ([elementName isEqualToString:#"landing"]) {
...............
} else if ...........
}