nsmutablearray elements to nsstring

Question

I want to retrieve elements that are parsed in a NSMutableArray and store them into a NSString variable and then store them in NSMutableArray as NSString (because I want to display the content in a NSComboBox). I tried this but it dosen't work. Can you fix the problem, I can't fix it:

//--this is the parsing code : 
- (void)parser:(NSXMLParser *)parser 
didStartElement:(NSString *)elementName 
  namespaceURI:(NSString *)namespaceURI 
 qualifiedName:(NSString *)qualifiedName 
    attributes:(NSDictionary *)attributeDict {

    if ([elementName isEqualToString:@"user"]) {
        NSLog(@"user element found – create a new instance of User class...");
        if(currentElementValue == nil)
            currentElementValue = [NSMutableString string];
        else 
            [currentElementValue setString:@""];
    }
    else {
        currentElementValue = nil;
    }
        user = [[User alloc] init];


}

- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string {
    if (!currentElementValue) {
        // init the ad hoc string with the value     
        currentElementValue = [[NSMutableString alloc] initWithString:string];
    } else {
        // append value to the ad hoc string    
        [currentElementValue appendString:string];
        if (currentElementValue) 
        {
            currentElementValue = nil;
        }
    }
    NSLog(@"Processing value for : %@", string);
}  

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

    if ([elementName isEqualToString:@"users"]) {
        // We reached the end of the XML document
        return;
        NSLog(@"QUIT");
    }
    if ([elementName isEqualToString:@"userName"]) {
        [[self user] setUserName:currentElementValue];
        NSLog(@"final step for value: %@", user.userName);
        NSLog(@"currentElementName content : %@", currentElementValue);
        [currentElementValue release];
        NSLog(@"release : %@", currentElementValue);
        currentElementValue = nil;
        NSLog(@"release : %@", currentElementValue);
    }
    if ([elementName isEqualToString:@"firstName"]) {
        [[self user] setFirstName:currentElementValue];
        [currentElementValue release];
        currentElementValue = nil;
    }

    if ([elementName isEqualToString:@"lastName"]) {
        [[self user] setLastName:currentElementValue];
        [currentElementValue release];
        currentElementValue = nil;
    }

    if ([elementName isEqualToString:@"user"]) {
        NSLog(@"\n user=%@ \n",user);

        [users addObject:user];
        NSLog(@"userName test : %@", users);

        [user release];
        user = nil;
    }
}
-(BOOL)parseDocumentWithData:(NSData *)data {

    if (data == nil)
        return NO;
    NSXMLParser *xmlparser = [[NSXMLParser alloc] initWithData:data];
    [xmlparser setDelegate:self];
    [xmlparser setShouldResolveExternalEntities:NO];

    BOOL ok = [xmlparser parse];
    if (ok == NO)
        NSLog(@"error");
    else
        NSLog(@"OK");

    [xmlparser release];
    return ok;
}

// this is the xml file : 

<users>
 <user>
  <userName>mspeller</userName>
  <firstName>Mike</firstName>
  <lastName>Speller</lastName>
 </user>
 <user>
  <userName>mgdan</userName>
  <firstName>Mila</firstName>
  <lastName>Gdan</lastName>
 </user>

</users>


//-------
NSMutableArray *tabletest= [[NSMutableArray alloc] init];
NSMutableString * result = [[NSMutableString alloc] init];
int i;
for(i=0; i < [users count]; i++){

    [result appendString:[NSString stringWithFormat:@"%@",[[users objectAtIndex:i] valueForKey:@"userName"]] ];
    NSLog(@"result==%@",result);

    [tabletest addObject:result];
}

Answer 1

Based on your link in the comment section I think you're accessing the "userName" property the wrong way. You're trying to access it, as users contains NSDictionary objects. As far as I can see you're adding User objects to the NSMutableArray.

Try the following (I took the liberty to beautify the code a bit):

NSMutableArray *tabletest= [NSMutableArray array];

for (User* user in users)
{
    NSString* result = [NSString stringWithFormat:@"%@", user.userName];
    NSLog(@"result==%@",result);

    [tabletest addObject:result];
}

Please correct me if I totally misunderstood your design.

Answer 2

I don't follow what your intention is, but what your code does at the moment is add the same string [user count] time to the array tabletest as follows:

The line:

[result appendString:[NSString stringWithFormat:@"%@",[[users objectAtIndex:i] valueForKey:@"userName"]] ];

accumulates into result the result of appending each [[users objectAtIndex:i] valueForKey:@"userName"] together - each iteration of the loop adds the next item to the end of result.

The line:

[tabletest addObject:result];

Adds the object referenced by result into the array. This is done once per iteration so the array ends up with [users count] references to the same object. Placing a reference to a mutable string into an array does not place a copy of its current value, just a reference to the string - mutate the string and the mutation is visible through the reference stored in the array.

So the final result of your code is an array of [users count] references to the same mutable string, and that string is the concatenation of all the [[users objectAtIndex:i] valueForKey:@"userName"] values.

What was your intent?

If you are trying to create an array of string representations of [[users objectAtIndex:i] valueForKey:@"userName"] then change the code to:

NSMutableArray *tabletest= [[NSMutableArray alloc] init];

for(int i = 0; i < [users count]; i++)
{
   // create a string representation of userName
   NSString *result = [NSString stringWithFormat:@"%@",[[users objectAtIndex:i] objectForKey:@"userName"]];
   // add the string to the array
   [tabletest addObject:result];
}

But maybe your intent is something else?