使用NSXMLParser解析XML并获取特定的属性值

Question

UPDATE: I decided to change my web service to output JSON, much easier to work with. I'll leave this open incase anyone can come up with a sensible solution, and in case it helps others.

I'm grabbing an XML file, parsing it, and trying to get content from specific tags:

//Grab the hosted XML
    NSError *error;
    NSURL *mainContentURL = [NSURL URLWithString:@"http://www.andrewlarking.co.uk/DigiCons/appContent.xml"];
    NSString *mainPageContents = [NSString stringWithContentsOfURL:mainContentURL encoding:NSUTF8StringEncoding error:&error];
    NSData *mainPageData = [mainPageContents dataUsingEncoding:NSUTF8StringEncoding];
    NSLog(@"mainPageData returned = %@", [[NSString alloc] initWithData:mainPageData encoding:NSUTF8StringEncoding]);

    //Parse the XML
    NSXMLParser *parser = [[NSXMLParser alloc] initWithData:mainPageData];
    [parser setDelegate:self];
    [parser parse];
}
}

-(void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary *)attributeDict{
    NSLog(@"In parser");
    if([elementName isEqualToString:@"feb5Content"])
    {
        NSLog(@"In elementname");
        NSLog(@"valueforkey title = %@", [attributeDict valueForKey:@"page.title"]);
        self.dcViewControllerLabel.text = [attributeDict valueForKey:@"page.title"];
    }
}

All is good, but the value for key@"page.title" or @"title" returns null. Here is the XML:

    <feb5Content>
<page>
<title>I am a test title.</title>
<subTitle>I am the subtitle.</subTitle>
</page>
</feb5Content>

Any thoughts?

Ideally I'd like to be able to grab the content of various elements that exist within the element. So I could have title, subTitle, bodyText all under and I'd need to grab those. Each page of the app will have it's contents stored in a element.

Cheers.

Answer 1

That's because your page title is not an attribute of the <feb5Content> element. It is the value of the <title> element. So you have to listen to the start of the <title> element:

-(void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary *)attributeDict{
   self.isTitleElement = [elementName isEqualToString:@"title"];
} 

And then in the following method get the value inside the <title> element:

- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string {
   if (self.isTitleElement) {
      NSLog(@"valueforkey title = %@", string);
      // store value so that it is not overwritten by the next title
      [self.pageTitles addObject:string];
   }
}

This method is called everytime that text is found inside an XML element. So you have to check if you are inside the <title> element when this method is called. That's why I included the ivar self.isTitleElement .

To store the page titles you can put them into an NSMutableArray ivar.