Help me out Strange issue when parsing - iphone

Question

I am having a strange problem when using this XML-to-NSDictionary class.really it was working great.
suddenly we found one weired problem using this.Let me explain this...when i have only one item the app is crashing. but when i have more than one item the app is not crashing.
When i have only one item to parse , after parsing if i print the count it shows as 6
But when i have more than one item, after parsing when i print the count it shows correctly
**
crash log:-
-[NSCFString objectAtIndex:]: unrecognized selector sent to instance
0x5c9a040 Terminating app due to
uncaught exception
'NSInvalidArgumentException', reason:
'-[NSCFString objectAtIndex:]:
unrecognized selector sent to instance
0x5c9a040'
**
Please help me out and thanks for your time
Source code
-(void)RequestUpdate
{
NSDictionary *mailDict = [[XMLReader dictionaryForXMLString:responseXML error:nil]
valueForKeyPath:#"response.mails.mail"];
NSLog(#"MAILS>MAIL COUNT %d %#", [mailDict count], mailDict);
}
#import "XMLReader.h"
NSString *const kXMLReaderTextNodeKey = #"text";
#interface XMLReader (Internal)
- (id)initWithError:(NSError **)error;
- (NSDictionary *)objectWithData:(NSData *)data;
#end
#implementation XMLReader
#pragma mark -
#pragma mark Public methods
+ (NSDictionary *)dictionaryForXMLData:(NSData *)data error:(NSError **)error
{
XMLReader *reader = [[XMLReader alloc] initWithError:error];
NSDictionary *rootDictionary = [reader objectWithData:data];
[reader release];
return rootDictionary;
}
+ (NSDictionary *)dictionaryForXMLString:(NSString *)string error:(NSError **)error
{
NSData *data = [string dataUsingEncoding:NSUTF8StringEncoding];
return [XMLReader dictionaryForXMLData:data error:error];
}
#pragma mark -
#pragma mark Parsing
- (id)initWithError:(NSError **)error
{
if ((self = [super init]))
{
errorPointer = error;
}
return self;
}
- (void)dealloc
{
[dictionaryStack release];
[textInProgress release];
[super dealloc];
}
- (NSDictionary *)objectWithData:(NSData *)data
{
// Clear out any old data
[dictionaryStack release];
[textInProgress release];
dictionaryStack = [[NSMutableArray alloc] init];
textInProgress = [[NSMutableString alloc] init];
// Initialize the stack with a fresh dictionary
[dictionaryStack addObject:[NSMutableDictionary dictionary]];
// Parse the XML
NSXMLParser *parser = [[[NSXMLParser alloc] initWithData:data] autorelease];
parser.delegate = self;
BOOL success = [parser parse];
// Return the stack's root dictionary on success
if (success)
{
NSDictionary *resultDict = [dictionaryStack objectAtIndex:0];
return resultDict;
}
return nil;
}
#pragma mark -
#pragma mark NSXMLParserDelegate methods
- (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary *)attributeDict
{
// Get the dictionary for the current level in the stack
NSMutableDictionary *parentDict = [dictionaryStack lastObject];
// Create the child dictionary for the new element, and initilaize it with the attributes
NSMutableDictionary *childDict = [NSMutableDictionary dictionary];
[childDict addEntriesFromDictionary:attributeDict];
// If there's already an item for this key, it means we need to create an array
id existingValue = [parentDict objectForKey:elementName];
if (existingValue)
{
NSMutableArray *array = nil;
if ([existingValue isKindOfClass:[NSMutableArray class]])
{
// The array exists, so use it
array = (NSMutableArray *) existingValue;
}
else
{
// Create an array if it doesn't exist
array = [NSMutableArray array];
[array addObject:existingValue];
// Replace the child dictionary with an array of children dictionaries
[parentDict setObject:array forKey:elementName];
}
// Add the new child dictionary to the array
[array addObject:childDict];
}
else
{
// No existing value, so update the dictionary
[parentDict setObject:childDict forKey:elementName];
}
// Update the stack
[dictionaryStack addObject:childDict];
}
- (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName
{
// Update the parent dict with text info
NSMutableDictionary *dictInProgress = [dictionaryStack lastObject];
// Set the text property
if ([textInProgress length] > 0)
{
[dictInProgress setObject:textInProgress forKey:kXMLReaderTextNodeKey];
// Reset the text
[textInProgress release];
textInProgress = [[NSMutableString alloc] init];
}
// Pop the current dict
[dictionaryStack removeLastObject];
}
- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string
{
// Build the text value
[textInProgress appendString:string];
}
- (void)parser:(NSXMLParser *)parser parseErrorOccurred:(NSError *)parseError
{
// Set the error pointer to the parser's error object
*errorPointer = parseError;
}
#end
Sample XML Data
<response>
<mails>
<mail id="4e12a3b04ff5ae0774000082">
<created_on>2011-07-05T05:40:00+00:00</created_on>
<updated_on>2011-07-05T05:40:00+00:00</updated_on>
<creator id="4e0abdff54b53058ff0000a2"><name>Merk Warn</name></creator>
<text>eee</text>
</mail>
<mail id="4e12dcvxva3b04ff5ae0774000082">
<created_on>2011-07-05T05:40:00+00:00</created_on>
<updated_on>2011-07-05T05:40:00+00:00</updated_on>
<creator id="4e0abdff54b53058ff0000a2"><name>Merk Warn</name></creator>
<text>eee</text>
</mail>
</mails>
</response>

Answer 1

That's because the tag is stored directly as an NSDictionary object if there is only one element. The count you are getting is the number of key-value pairs in a dictionary.
You can handle this differently,
-(void)update
{
id value = [[XMLReader dictionaryForXMLString:responseXML error:nil] valueForKeyPath:#"response.mails.mail"];
NSArray * mails;
if ( [value isKindOfClass:[NSDictionary class]] ) {
mails = [NSArray arrayWithObject:value];
}
else {
mails = (NSArray *)value;
}
/* `mails` is an array of <mail> based dictionaries */
}
You will have to retain it appropriately.