Why are my arrays showing up as empty, even after I've added values to them?

Question

I am parsing XML with NSXMLParser and I have some NSMutableArrays (instance variables) in my app. When I parse the XML file, I build objects with the values of the XML elements, and set my array with those objects.

In the moment that I set my array with those objects I can see the values of them. But once I have finished parsing the XML I want to retrieve those values and the array is now empty.

Here is a part of my code:

//STHelpViewController.h

#import <UIKit/UIKit.h>

@class SoftokeniPhoneAppDelegate, FAQ;
@interface STHelpViewController : UIViewController {
    UIView *viewAnswer;
    UINavigationBar *answerTitle;
    UIButton *answerDescription;
    NSArray *answersArray;
    NSMutableArray *faqs;     //THIS IS MY ARRAY WITH THE PROBLEM
    NSMutableString *currentElementValue;   
    FAQ *aFAQ;

    NSString* Answer1;
    NSString* Answer2;
    NSString* Answer3;
    NSString* Answer4;
}

@property (nonatomic, retain) IBOutlet  UIView *viewAnswer;
@property (nonatomic, retain) IBOutlet  UINavigationBar *answerTitle;
@property (nonatomic, retain) IBOutlet  UIButton *answerDescription;
@property (nonatomic, retain) NSMutableArray *faqs;

@property (nonatomic, retain)NSString* Answer1; 
@property (nonatomic, retain)NSString* Answer2; 
@property (nonatomic, retain)NSString* Answer3; 
@property (nonatomic, retain)NSString* Answer4; 


@end





//STHelpViewController.m


- (void)viewDidLoad {
    [super viewDidLoad];
    NSURL *url = [[NSURL alloc] initWithString:@"http://clientes.imit.cl/MovilPass/faq.xml"];
    NSXMLParser *xmlParser = [[NSXMLParser alloc] initWithContentsOfURL:url];

    //Initialize the delegate.
    STHelpViewController *parser = [[STHelpViewController alloc] initXMLParser];

    //Set delegate
    [xmlParser setDelegate:parser];

    //Start parsing the XML file.
    BOOL success = [xmlParser parse];

    if(success){
        NSLog(@"F.A.Q. loaded from XMl file");

        //HERE IS THE PROBLEM. AT THIS PART XCODE SAYS THAT faqs(my array) IS EMPTY

        Answer1 = [[[faqs objectAtIndex:0] valueForKey:@"Respuesta"]description];
        Answer2 = [[[faqs objectAtIndex:1] valueForKey:@"Respuesta"]description];
        Answer3 = [[[faqs objectAtIndex:2] valueForKey:@"Respuesta"]description];
        Answer4 = [[[faqs objectAtIndex:3] valueForKey:@"Respuesta"]description];
        answersArray = [[NSArray alloc] initWithObjects:Answer1,Answer2,Answer3,Answer4,nil];
    }
    else
    {
        NSLog(@"Error loading XML file for F.A.Q. Default data loaded instead.");
        answersArray = [[NSArray alloc] 
                        initWithObjects:@"El Movilpass es una nueva herramienta de Bci Móvil que le permitirá obtener la clave de  ocho dígitos desde su celular, sin tener que llevar el dispositivo electrónico. Regístrese para recibir la aplicación, cárguela en su Iphone y sincronícela.", 
                        @"El Movilpass es igual de válido que el dispositivo electrónico.  Sólo debe sincronizarlo correctamente en su celular, siguiendo uno a uno los pasos que le indiquen.",
                        @"Para sincronizar, presione el botón “Ajustes”, luego “Sincronizar” y obtendrá los siguientes pasos:\n \n Ingrese a su banca Internet. \n Entre a Seguridad y Emergencia. \n Click en Movilpass. \n Seleccione el botón 'Sincronizar'.",
                        @"Si se le perdió su TELEFONO, lo primero que debe hacer es llamar al 600 8242424 para que lo bloqueen. Una vez que obtenga el nuevo aparato, podrá solicitar nuevamente su Movilpass.", 
                        nil];   
    }                                   
}


- (STHelpViewController *) initXMLParser {

    [super init];

    //appDelegate = (SoftokeniPhoneAppDelegate *)[[UIApplication sharedApplication] delegate];

    return self;
}

- (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName
  namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qualifiedName
    attributes:(NSDictionary *)attributeDict {
    if([elementName isEqualToString:@"PreguntasFrecuentes"]) {
        faqs = [[NSMutableArray new]retain];        
    }
    else if([elementName isEqualToString:@"Item"]) 
    {
        aFAQ = [[FAQ alloc] init];
        aFAQ.itemID = [[attributeDict objectForKey:@"id"] integerValue];        
        NSLog(@"Leyendo valor de atributo id: %i", aFAQ.itemID);
    }
    NSLog(@"Procesando Elemento: %@", elementName);
}

- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string {

    if(!currentElementValue)
        currentElementValue = [[NSMutableString alloc] initWithString:string];
    else
        [currentElementValue appendString:string];

    NSLog(@"Procesando Valor: %@", currentElementValue);

}

- (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName
  namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName {

    if([elementName isEqualToString:@"PreguntasFrecuentes"])
        return;
    if([elementName isEqualToString:@"Item"]) {
        [faqs addObject:aFAQ];
        [aFAQ release];
        aFAQ = nil; 
    }
    else
    {
        [aFAQ setValue:currentElementValue forKey:elementName];     
    }
    [currentElementValue release];
    currentElementValue = nil;

    //IF I PRINT MY ARRAY HERE, I CAN SEE THE VALUES
}

What could I be doing wrong?

Answer 1

1. In viewDidLoad you're allocating another STHelpViewController for no good reason. Do this instead,

    - (void)viewDidLoad {
        [super viewDidLoad];
        NSURL *url = [[NSURL alloc] initWithString:@"http://clientes.imit.cl/MovilPass/faq.xml"];
        NSXMLParser *xmlParser = [[NSXMLParser alloc] initWithContentsOfURL:url];
        [url release];

        //I am the delegate
        [xmlParser setDelegate:self];

        //Start parsing the XML file.
        BOOL success = [xmlParser parse];

        //NSLog(@"Count My FAQ %d", [[self faqs] count]); Uncomment for debugging.
        ...
    }

---

2. If you don't use self you have to fix initXMLParser. You must always use the designated initializer of you super class and assign to the ivar self. Like so,

    - (STHelpViewController *) initXMLParser {
        if(self = [super init]) {
            //alloc and init any ivar you want
        }
        return self;
    }

And then do this,

    - (void)viewDidLoad {
        [super viewDidLoad];
        NSURL *url = [[NSURL alloc] initWithString:@"http://clientes.imit.cl/MovilPass/faq.xml"];
        NSXMLParser *xmlParser = [[NSXMLParser alloc] initWithContentsOfURL:url];
        [url release];

        //Initialize the delegate.
        STHelpViewController *parser = [[STHelpViewController alloc] initXMLParser];

        //Set delegate
        [xmlParser setDelegate:parser];

        //Start parsing the XML file.
        BOOL success = [xmlParser parse];

        //Get results from parser
        NSArray parserFAQs = [parser faqs];
        [parser release];

        //NSLog(@"Count Parser's FAQ %d", [parserFAQs count]); Uncomment for debugging.
        ...
    }

Answer 2

You instantiate faqs = [[NSMutableArray new]retain]; on every didStartElement call. It seems weird to me. You should move faqs = [[NSMutableArray new]retain]; to your viewDidLoad.

Moreover, I don't see the necessity of retain there.