NSURLRequest: EXC_BAD_ACCESS

I'm building an application with loads content from an PHP file. I have 4 views with loads content from 4 different PHP files. For each view controller i'm using the following code:

//
//  turmaAViewController.m
//  SamplePad
//
//  Created by Mateus Nunes on 25/09/11.
//  Copyright 2011 NBM Company. All rights reserved.
//

#import "turmaAViewController.h"
#import "DetailViewController.h"

@implementation turmaAViewController

@synthesize messageList;
@synthesize studentImageView;
@synthesize imageText;

//###############################################################################
//############################################################ DEVICE ORIENTATION
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation{

    if(interfaceOrientation == UIInterfaceOrientationLandscapeRight){ 
        return YES;
    }
    else if(interfaceOrientation == UIInterfaceOrientationLandscapeLeft){
        return YES;
    }else
        return NO;
}

//##############################################################################################################################
//#################                           CUSTOM VIEW INITIALIZATION                                      #################//
//##############################################################################################################################
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil {
    if ((self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil])) {
        lastId = 0;
        chatParser = NULL;
    }
    return self;
}

//##############################################################################################################################
//#################                           DEALLOC - MEMORY RELEASE                                       #################//
//##############################################################################################################################
-(void)dealloc {
    [messageList release];
    [super dealloc];
}

//##############################################################################################################################
//#################                           DISPLAY PHP FILE INTEGRATION                                   #################//
//##############################################################################################################################
-(void)getNewMessages {

    NSString *url = [NSString stringWithFormat:@"http://localhost/SPA/turmaa.php?past=%ld&t=%ld",lastId, time(0) ];

    NSMutableURLRequest *request = [[[NSMutableURLRequest alloc] init] autorelease];
    [request setURL:[NSURL URLWithString:url]];
    [request setHTTPMethod:@"GET"];

    NSURLConnection *conn=[[NSURLConnection alloc] initWithRequest:request delegate:self];  

    if (conn){  
        receivedData = [[NSMutableData data] retain];  
    }else{}  

}
- (NSCachedURLResponse *)connection:(NSURLConnection *)connection willCacheResponse:(NSCachedURLResponse *)cachedResponse {
    return nil;
}

//##############################################################################################################################
//#################                                FETCHING PRAGMAS                                          #################//
//##############################################################################################################################
-(void)timerCallback {
    [timer release];
    [self getNewMessages];
}

//##############################################################################################################################
//#################                             CONNECTION PRAGMAS                                           #################//
//##############################################################################################################################
-(void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response {
    [receivedData setLength:0];
}  
-(void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {
    [receivedData appendData:data];
}  
-(void)connectionDidFinishLoading:(NSURLConnection *)connection  {  

    if (chatParser)
        [chatParser release];

    if (messages == nil)

        messages = [[NSMutableArray alloc] init];

    chatParser = [[NSXMLParser alloc] initWithData:receivedData];
    [chatParser setDelegate:self];
    [chatParser parse];

    [receivedData release];  
    [messageList reloadData];

    NSInvocation *invocation = [NSInvocation invocationWithMethodSignature:[self methodSignatureForSelector: @selector(timerCallback)]];
    //[invocation setTarget:self];
    [invocation setSelector:@selector(timerCallback)];
    //timer = [NSTimer scheduledTimerWithTimeInterval:5.0 invocation:invocation repeats:NO];
}  

//##############################################################################################################################
//#################                         PARSING THE MESSAGE XML FILE LIST                                #################//
//##############################################################################################################################
-(void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary *)attributeDict {

    if ( [elementName isEqualToString:@"message"] ) {

        msgAdded = [[attributeDict objectForKey:@"added"] retain];
        msgId = [[attributeDict objectForKey:@"id"] intValue];

        msgAluno     = [[NSMutableString alloc] init];
        msgMatricula = [[NSMutableString alloc] init];
        msgCpf       = [[NSMutableString alloc] init];
        msgImage     = [[NSMutableString alloc] init];
        msgCC   = [[NSMutableString alloc] init];

        inAluno   = NO;
        inMatricula   = NO;
        inCpf  = NO;
        inImage  = NO;
        inCC  = NO;
    }
    if ( [elementName isEqualToString:@"aluno"]     )  { inAluno = YES;}
    if ( [elementName isEqualToString:@"matricula"] )  { inMatricula = YES;}
    if ( [elementName isEqualToString:@"cpf"]       )  { inCpf = YES;}
    if ( [elementName isEqualToString:@"image"]     )  { inImage = YES;}
    if ( [elementName isEqualToString:@"CC"]  )  { inCC = YES;}


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

    if ( inAluno )      { [msgAluno appendString:string]; }
    if ( inMatricula )  { [msgMatricula appendString:string]; }
    if ( inCpf )        { [msgCpf appendString:string]; }
    if ( inImage )      { [msgImage appendString:string];}
    if ( inCC )         { [msgCC appendString:string];}

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

    if ( [elementName isEqualToString:@"message"] ) {

        [messages addObject:[NSDictionary dictionaryWithObjectsAndKeys:msgAdded,@"added",msgAluno,@"aluno",msgMatricula,@"matricula",msgCpf,@"cpf",msgImage,@"image",msgCC,@"CC",nil]];

        [[messages reverseObjectEnumerator] allObjects];

        lastId = msgId;

        [msgAdded release];
        [msgAluno release];
        [msgMatricula release];
        [msgCpf release];
        [msgImage release];
        [msgCC release];

    }

    if ( [elementName isEqualToString:@"aluno"]     ) { inAluno = NO;}
    if ( [elementName isEqualToString:@"matricula"] ) { inMatricula = NO;}
    if ( [elementName isEqualToString:@"cpf"]       ) { inCpf = NO;}
    if ( [elementName isEqualToString:@"image"]     ) { inImage = NO;}
    if ( [elementName isEqualToString:@"CC"]  ) { inCC = NO;}
}

//##############################################################################################################################
//#################                         PARSING FINISHED - START DISPLAYING                              #################//
//##############################################################################################################################
-(NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
    return 1;
}
-(NSInteger)tableView:(UITableView *)myTableView numberOfRowsInSection:(NSInteger)section {
    return ( messages == nil ) ? 0 : [messages count];
}
-(UITableViewCell *)tableView:(UITableView *)myTableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {

    UITableViewCell *cell = (UITableViewCell *)[self.messageList dequeueReusableCellWithIdentifier:@"newsCustomCell"];
    if (cell == nil) {
        NSArray *nib = [[NSBundle mainBundle] loadNibNamed:@"newsCustomCell" owner:self options:nil];
        cell = (UITableViewCell *)[nib objectAtIndex:0];
    }

    NSDictionary *itemAtIndex = (NSDictionary *)[messages objectAtIndex:indexPath.row];

    UILabel *timeDate = (UILabel *)[cell viewWithTag:1];
    timeDate.text = [itemAtIndex objectForKey:@"added"];

    UILabel *userL = (UILabel *)[cell viewWithTag:2];
    userL.text = [itemAtIndex objectForKey:@"aluno"];

    UILabel *textL = (UILabel *)[cell viewWithTag:3];
    textL.text = [itemAtIndex objectForKey:@"matricula"];

    UILabel *textL2 = (UILabel *)[cell viewWithTag:4];
    textL2.text = [itemAtIndex objectForKey:@"cpf"];

    UILabel *imageL = (UILabel *)[cell viewWithTag:5];
    imageL.text = [itemAtIndex objectForKey:@"image"];

    UILabel *videoL = (UILabel *)[cell viewWithTag:6];
    videoL.text = [itemAtIndex objectForKey:@"CC"];

    UIWebView *webView = (UIWebView *) [cell viewWithTag:7];
    NSString *urlAddress = [itemAtIndex objectForKey:@"image"];
    NSURL *url = [NSURL URLWithString:urlAddress];
    NSURLRequest *requestObj = [NSURLRequest requestWithURL:url];
    [webView loadRequest:requestObj];

    return cell;
}

-(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {

    DetailViewController *dvController = [[DetailViewController alloc] initWithNibName:@"DetailViewController" bundle:[NSBundle mainBundle]];

    NSDictionary *itemAtIndex = (NSDictionary *)[messages objectAtIndex:indexPath.row];

    NSString *selectTime = [itemAtIndex objectForKey:@"added"];

    NSString *selectUser = [itemAtIndex objectForKey:@"aluno"];

    NSString *selectMessage = [itemAtIndex objectForKey:@"matricula"];

    NSString *selectMessage2 = [itemAtIndex objectForKey:@"cpf"];

    NSString *selectImage = [itemAtIndex objectForKey:@"image"];

    NSString *selectVideo = [itemAtIndex objectForKey:@"CC"];

    dvController.selectedTime = selectTime;
    dvController.selectedUser = selectUser;
    dvController.selectedImage = selectImage;
    dvController.selectedMessage = selectMessage;
    dvController.selectedMessage2 = selectMessage2;
    dvController.selectedVideo = selectVideo;


    [self.navigationController pushViewController:dvController animated:YES];
    [dvController release];
    dvController = nil;

    [tableView deselectRowAtIndexPath:indexPath animated:NO];

}


//##############################################################################################################################
//#################                         PARSING FINISHED - START DISPLAYING                              #################//
//#########################开发者_StackOverflow社区#####################################################################################################
-(void)viewDidLoad {    
    messageList.dataSource = self;
    messageList.delegate = self;

    [messageList release];


    [self getNewMessages];
    [super viewDidLoad];

}


@end

First when i build one view with this code and tested it had worked well, no problems. But when i added this code to the others views the application started crashing, "EXC_BAD_ACCESS" Error! Because of this i suppose i need to kill the request when i run out of my view, but how can i do this or if you identify another problem!

I will give you a hint, not the answer. EXC_BAD_ACCESS occurs when a method is called on an object that has been released. To see which object is being called, you will have to enable Zombies. To enable zombies in xcode 4, see How do I set up NSZombieEnabled in Xcode 4?.