NSMutableString issue with NSXMLParser - objective-c

Question

I am having a heck of a time with this -- I am trying to parse an XML file and set the text in a NSMutableString variable in order to later fill in a label's text as you can see below.
In my .h I have the following (simplified);
NSMutableString *contentsOfCurrentXMLProperty;
#property (nonatomic,retain) NSMutableString *contentsOfCurrentXMLProperty;
In my .m:
-(void) parseData {
NSXMLParser *parser = [[NSXMLParser alloc] initWithData:myData];
[parser setDelegate:self];
[parser parse];
[parser release];
}
- (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary *)attributeDict {
if ([elementName isEqualToString:#"Title"]) {
NSLog(#"FOUND TITLE!");
contentsOfCurrentXMLProperty = [NSMutableString setString:#""];
}
}
-(void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName {
if ([elementName isEqualToString:#"TITLE"]) {
myLabel.text = [contentsOfCurrentXMLProperty stringByReplacingOccurrencesOfString:#"[br]" withString:#"\n"];
}
}
- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string {
[self.contentsOfCurrentXMLProperty appendString:string];
}
When I run my app, the data is downloaded and parsed correctly. I run into issues when my observer fires off the event again. The parseData method is called and I get an error that I have traced to the line that reads: "contentsOfCurrentXMLProperty = [NSMutableString setString:#""];
"
What is the proper way to create or init a NSMutableString variable for me to use over and over? When/Where is the best place to release it? How do I essentially clear the variable so that when the observer fires off the parseData method it will again be able to set "contentsOfCurrentXMLProperty"?

Answer 1

-setString: is an instance method, not a class method. If you already have a valid NSMutableString object assigned to contentsOfCurrentXMLProperty and simply want to clear it, then:
contentsOfCurrentXMLProperty = [NSMutableString setString:#""];
should be
[contentsOfCurrentXMLProperty setString:#""];
On the other hand, if you want to assign a new object to contentsOfCurrentXMLProperty, here's one valid way to do it:
self.contentsOfCurrentXMLProperty = [NSMutableString stringWithCapacity:0];