iPhone - Parsing XML file - Please help! - iphone

Question

I need help with parsing a xml file. My problem is I don't know how to implement the didEndElement delegate.
What I want is that I will have 2 cells where Old Testament and New Testament will be displayed and then the Books of the Bible and the the chapters.
If I can just get some help with the xml parsing the rest I can manage.
Will be very grateful for any help!
Thanks and regards!
My xml file is as follows:
<?xml version="1.0" encoding="UTF-8"?>
<bible>
<testament name="Old Testament">
<book name="Genesis">
<chapter id="Genesis 1"></chapter>
<chapter id="Genesis 2"></chapter>
</book>
<book name="Exodus">
<chapter id="Exodus 1"></chapter>
<chapter id="Exodus 2"></chapter>
</book>
</testament>
<testament name="New Testament">
<book name="Matthew">
<chapter id="Matthew 1"></chapter>
<chapter id="Matthew 2"></chapter>
</book>
<book name="Revelation">
<chapter id="Revelation 1"></chapter>
<chapter id="Revelation 2"></chapter>
</book>
</testament>
</bible>
// Bible.h
#import <Foundation/Foundation.h>
#interface Bible : NSObject {
NSMutableArray *bible;
NSMutableArray *testament;
NSMutableArray *book;
NSString *chapterID;
}
#property (nonatomic, retain)NSMutableArray *bible;
#property (nonatomic, retain)NSMutableArray *testament;
#property (nonatomic, retain)NSMutableArray *book;
#property (nonatomic, retain)NSString *chapterID;
#end
// Bible.m
#import "Bible.h"
#implementation Bible
#synthesize bible;
#synthesize testament;
#synthesize book;
#synthesize chapterID;
- (void) dealloc {
[bible release];
[testament release];
[book release];
[chapterID release];
[super dealloc];
}
#end
//
// XMLParser.h
// BibleXML
//
#import <Foundation/Foundation.h>
#import "Bible.h"
#protocol NSXMLParserDelegate;
#class BibleXMLAppDelegate, Bible;
#interface XMLParser : NSObject <NSXMLParserDelegate> {
NSMutableString *currentElementValue;
BibleXMLAppDelegate *appDelegate;
Bible *theBible;
}
- (XMLParser *) initXMLParser;
#end
//
// XMLParser.m
#import "XMLParser.h"
#import "BibleXMLAppDelegate.h"
#import "Bible.h"
#implementation XMLParser
- (XMLParser *) initXMLParser {
[super init];
appDelegate = (BibleXMLAppDelegate *) [[UIApplication sharedApplication] delegate];
return self;
}
- (void)parserDidStartDocument:(NSXMLParser *)parser{
NSLog(#"found file and started parsing");
}
- (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName
namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qualifiedName
attributes:(NSDictionary *)attributeDict {
if([elementName isEqualToString:#"bible"]) {
NSLog(#"Found element: %#", elementName);
appDelegate.bible = [[NSMutableArray alloc] init];
}
else if([elementName isEqualToString:#"testament"]) {
theBible = [[Bible alloc] init];
//Extract the attribute here.
theBible.testament = [attributeDict valueForKey:#"name"];
NSLog(#"Testament: %#", theBible.testament);
return;
}
else if ([elementName isEqualToString:#"book"])
{
theBible.book = [attributeDict valueForKey:#"name"];
NSLog(#"Book: %#", theBible.book);
return;
}
else if([elementName isEqualToString:#"chapter"])
{
theBible.chapterID =[attributeDict objectForKey:#"id"];
NSLog(#"Chapter: %#", theBible.chapterID);
return;
}
}
- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string {
}
- (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName
namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName {
if([elementName isEqualToString:#"bible"]){
return;
}
}
- (void) dealloc {
[theBible release];
[currentElementValue release];
[super dealloc];
}
#end
Following is the output from the debugger console:
2010-12-08 19:53:10.101 BibleXML[25641:207] found file and started parsing
2010-12-08 19:53:10.102 BibleXML[25641:207] Found element: bible
2010-12-08 19:53:10.103 BibleXML[25641:207] Testament: Old Testament
2010-12-08 19:53:10.103 BibleXML[25641:207] Book: Genesis
2010-12-08 19:53:10.104 BibleXML[25641:207] Chapter: Genesis 1
2010-12-08 19:53:10.104 BibleXML[25641:207] Chapter: Genesis 2
2010-12-08 19:53:10.105 BibleXML[25641:207] Book: Exodus
2010-12-08 19:53:10.105 BibleXML[25641:207] Chapter: Exodus 1
2010-12-08 19:53:10.106 BibleXML[25641:207] Chapter: Exodus 2
2010-12-08 19:53:10.107 BibleXML[25641:207] Testament: New Testament
2010-12-08 19:53:10.107 BibleXML[25641:207] Book: Matthew
2010-12-08 19:53:10.108 BibleXML[25641:207] Chapter: Matthew 1
2010-12-08 19:53:10.108 BibleXML[25641:207] Chapter: Matthew 2
2010-12-08 19:53:10.109 BibleXML[25641:207] Book: Revelation
2010-12-08 19:53:10.109 BibleXML[25641:207] Chapter: Revelation 1
2010-12-08 19:53:10.110 BibleXML[25641:207] Chapter: Revelation 2
2010-12-08 19:53:10.110 BibleXML[25641:207] No Errors

Answer 1

You're already parsing it. In the didEndElement: call, just do whatever you want to do with the element. Since your XML doesn't contain any wrapped strings (you're not using foundCharacters:), all you have to do is respond to didStartElement: and didEndElement: accordingly. If you need to capture attributes or allocate a new data structure to hold possible children, do it in didStartElement:. If you need to save off objects into collections or somehow finish processing of a particular element, do it in didEndElement:.
This question isn't really about parsing, it's about whatever logic you want to enact in response to parsing.
Edit in response to comment below:
I typically do the following to save off objects during parsing: in my interface, I declare the collection I need to save objects into and a temporary object that I used to hold whatever data I need to before adding it to the collection, like this
#interface MyClass : NSObject <NSXMLParserDelegate>{
NSMutableArray *collection_;
SomeObject *tempObject_;
}
#end
In the implementation I manipulate these two objects, typically in didStartDocument:, didStartElement: and didEndElement:, like so:
- (void)parserDidStartDocument:(NSXMLParser *)parser {
collection_ = [[NSMutableArray alloc] init];
}
- (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qualifiedName attributes:(NSDictionary *)attributeDict {
//if your object is tied to a tag that wraps text (delivered in foundCharacters:), initialize it here
tempObject_ = [[SomeObject alloc] init];
//maybe you need the attributes....
tempObject_.someProperty = [attributes objectForKey:#"attribute-name"];
}
- (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName {
//when the tag ends, you can save it off into the collection
[collection_ addObject:tempObject_];
[tempObject_ release];
tempObject_ = nil;
}
Then do what you will with the collection object. Make sure you handle memory things, like releasing the collection object or whatever. I usually use something like a delegate callback (of my own devising) to get the collection to the model, in order to logically separate parsing from the model.