problem with unloading view. app get crashed

In my application

It do have tableview... with two rows.

1. Date.
2. City.

When selected Date ...i load EventViewController view which working well and good...

when getting back to my tableview and selected City my app get crashed

I do not see any thing in my console. its not showing any message.

What to do...

here is the code....

The For implementation......

but my app get crashed...

  #import "SearchViewController.h"
    #import "SearchDetailViewController.h"
    #import "EventViewController.h"

    @implementation SearchViewController
    @synthesize searchListArray;
    /*
     // The designated initializer.  Override if you create the controller programmatically and want to perform customization that is not appropriate for viewDidLoad.
    - (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil {
        if ((self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil])) {
            // Custom initialization
        }
        return self;
    }
    */


    // Implement viewDidLoad to do additional setup after loading the view, typically from a nib.
    - (void)viewDidLoad {
        [super viewDidLoad];
        UIBarButtonItem *barButton=[[UIBarButtonItem alloc]initWithTitle:@"Back" style:UIBarButtonItemStylePlain target:nil action:nil];
        self.navigationItem.backBarButtonItem=barButton;
        [barButton release];
        searchListArray =[[NSMutableArray alloc]init];
        [searchListArray addObject:@"City"];
        [searchListArray addObject:@"Populair"];
        [searchListArray addObject:@"Date"];
    }

    - (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
            // Return the number of sections.
        return 1;
    }

    - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
            // Return the number of rows in the section.
        return [searchListArray count];
    }

        // Customize the appearance of table view cells.
    - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
        static NSString *CellIdentifier = @"Cell";

        UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier]; 
        if (cell == nil) {
            cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier] autorelease];
            cell.selectionStyle= UITableViewCellSelectionStyleBlue;
    //      cell.accessoryType=UITableViewCellAccessoryDisclosureIndicator;
            cell.backgroundColor=[UIColor blueColor];
            cell.textLabel.text=[searchListArray objectAtIndex:indexPath.row];
            switch (indexPath.row) {
                case 0:
                    cell.accessoryType=UITableViewCellAccessoryDisclosureIndicator;
                    break;
                    case 2:
                    cell.accessoryType=UITableViewCellAccessoryDisclosureIndicator;
                    break;

                default:
                    break;

            }
        }
        return cell;

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

        switch (indexPath.row) {
            case 0:
                NSLog(@"searchdetailedview");
                SearchDetailViewController *searchDetailViewController = [[SearchDetailViewController alloc] initWithNibName:@"SearchDetailViewController" bundle:nil];
                [self.navigationController pushViewController:searchDetailViewController animated:YES];
                    //  self.navigationItem.title = @"Back"; 
                [searchDetailViewController release];
                searchDetailViewController=nil;
                break;
                case 2:
                NSLog(@"eventviewController");

                EventViewController *eventViewController=[[EventViewController alloc]initWithNibName:@"EventViewController" bundle:nil];
                [self.navigationController pushViewController:eventViewController animated:YES];
                [eventViewController release];
                eventViewController=nil;
                break;
            default:
                break;
        }   
    }



    /*
    // Override to allow orientations other than the default portrait orientation.
    - (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {
        // Return YES for supported orientations
        return (interfaceOrientation == UIInterfaceOrientationPortrait);
    }
    */



    - (void)didReceiveMemoryWarning {
        // Releases the view if it doesn't have a superview.
        [super didReceiveMemoryWarning];

        // Release any cached data, images, etc that aren't in use.
    }

    - (void)viewDidUnload {
        [super viewDidUnload];
        // Release any retained subviews of the main view.
        // e.g. self.myOutlet = nil;
    }


    - (void)dealloc {
        [searchListArray release];
        [super dealloc];
    }

EventViewController

#import "EventViewController.h"

    @implementation EventViewController
    @synthesize eventsList;
    @synthesize eventStore;
    @synthesize defaultCalendar;
    @synthesize detailViewController;

    #pragma mark -
    #pragma mark View lifecycle


    - (void)viewDidLoad {
        [super viewDidLoad];
        self.title=@"Event List";
        self.eventStore=[[EKEventStore alloc]init];
        self.eventsList=[[NSMutableArray alloc]initWithArray:0];
        self.defaultCalendar=[self.eventStore defaultCalendarForNewEvents];
            // Uncomment the following line to display an Edit button in the navigation bar for this view controller.
        UIBarButtonItem *addButtonItem = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:
                                          UIBarButtonSystemItemAdd target:self action:@selector(addEvent:)];
        self.navigationItem.rightBarButtonItem = addButtonItem;
        [addButtonItem release];
        self.navigationController.delegate = self;
        [self.eventsList addObjectsFromArray:[self fetchEventsForToday]];
        [self.tableView reloadData];
    }

    - (IBAction) addEvent:(id)sender{
        EKEventEditViewController *addController = [[EKEventEditViewController alloc] initWithNibName:nil bundle:nil];
            // set the addController's event store to the current event store.
        addController.eventStore = self.eventStore;
            // present EventsAddViewController as a modal view controller
        [self presentModalViewController:addController animated:YES];
        addController.editViewDelegate = self;
        [addController release];
    }

    - (NSArray *) fetchEventsForToday{

        NSDate *startDate = [NSDate date];
            // endDate is 1 day = 60*60*24 seconds = 86400 seconds from startDate
        NSDate *endDate = [NSDate dateWithTimeIntervalSinceNow:86400];
            // Create the predicate. Pass it the default calendar.
        NSArray *calendarArray = [NSArray arrayWithObject:defaultCalendar];
        NSPredicate *predicate = [self.eventStore predicateForEventsWithStartDate:startDate endDate:endDate 
                                                                        calendars:calendarArray]; 
            // Fetch all events that match the predicate.
        NSArray *events = [self.eventStore eventsMatchingPredicate:predicate];
        return events;
    }

    - (void)viewWillAppear:(BOOL)animated {
            //    [super viewWillAppear:animated];
        [self.tableView deselectRowAtIndexPath:self.tableView.indexPathForSelectedRow animated:NO];  

    }


    /*
    - (void)viewDidAppear:(BOOL)animated {
        [super viewDidAppear:animated];
    }
    */
    /*
    - (void)viewWillDisappear:(BOOL)animated {
        [super viewWillDisappear:animated];
    }
    */
    /*
    - (void)viewDidDisappear:(BOOL)animated {
        [super viewDidDisappear:animated];
    }
    */

    // Override to allow orientations other than the default portrait orientation.
    - (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {
        // Return YES for supported orientations
        return (interfaceOrientation == UIInterfaceOrientationPortrait);
    }



    #pragma mark -
    #pragma mark Table view data source

    //- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
    //    // Return the number of sections.
    //  // return <#number of sections#>;
    //}


    - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
        // Return the number of rows in the section.
         return [eventsList count];
    }


    // Customize the appearance of table view cells.
    - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {

        static NSString *CellIdentifier = @"Cell";
        UITableViewCellAccessoryType editableCellAccessoryType =UITableViewCellAccessoryDisclosureIndicator;


        UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
        if (cell == nil) {
            cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];
        }
        cell.accessoryType=editableCellAccessoryType;
        cell.textLabel.text=[[self.eventsList objectAtIndex:indexPath.row]title];
        // Configure the cell...

        return cell;
    }


    /*
    // Override to support conditional editing of the table view.
    - (BOOL)tableView:(UITableView *)tableView canEditRowAtIndexPath:(NSIndexPath *)indexPath {
        // Return NO if you do not want the specified item to be editable.
        return YES;
    }
    */


    /*
    // Override to support editing the table view.
    - (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath {

        if (editingStyle == UITableViewCellEditingStyleDelete) {
            // Delete the row from the data source
            [tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
        }   
        else if (editingStyle == UITableViewCellEditingStyleInsert) {
            // Create a new instance of the appropriate class, insert it into the array, and add a new row to the table view
        }   
    }
    */


    /*
    // Override to support rearranging the table view.
    - (void)tableView:(UITableView *)tableView moveRowAtIndexPath:(NSIndexPath *)fromIndexPath toIndexPath:(NSIndexPath *)toIndexPath {
    }
    */


    /*
    // Override to support conditional rearranging of the table view.
    - (BOOL)tableView:(UITableView *)tableView canMoveRowAtIndexPath:(NSIndexPath *)indexPath {
        // Return NO if you do not want the item to be re-orderable.
        return YES;
    }
    */


    #pragma mark -
    #pragma mark Table view delegate

    - (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
    // Navigation logic may go here. Create and push another view controller.
    // Upon selecting an event, create an EKEventViewController to display the event.
        self.detailViewController = [[EKEventViewController alloc] initWithNibName:nil bundle:nil];         
        detailViewController.event = [self.eventsList objectAtIndex:indexPath.row];
    // Allow event editing.
        detailViewController.allowsEditing = YES;
    //  Push detailViewController onto the navigation controller stack
    //  If the underlying event gets deleted, detailViewController will remove itself from
    //  the stack and clear its event property.
        [self.navigationController pushViewController:detailViewController animated:YES];

    }


    #pragma mark -
    #pragma mark Navigation Controller delegate

    - (void)navigationController:(UINavigationController *)navigationController 
          willShowViewController:(UIViewController *)viewController animated:(BOOL)animated{
        if (viewController == self && self.detailViewController.event.title == NULL) {
            [self.eventsList removeObject:self.detailViewController.event];
            [self.tableView reloadData];
        }
    }

    - (void)eventEditViewController:(EKEventEditViewController *)controller 
              didCompleteWithAction:(EKEventEditViewAction)action{
        NSError *error=nil;
        EKEvent *thisEvent=controller.event;
        switch (action) {
            case EKEventEditViewActionCanceled:
                break;
            开发者_JAVA技巧case EKEventEditViewActionSaved:
                if (self.defaultCalendar ==thisEvent.calendar) {
                    [self.eventsList addObject:thisEvent];
                }
                [controller.eventStore saveEvent:controller.event span:EKSpanThisEvent error:&error];
                [self.tableView reloadData];
                break;
            case EKEventEditViewActionDeleted:
                if (self.defaultCalendar ==  thisEvent.calendar) {
                    [self.eventsList removeObject:thisEvent];
                }
                [controller.eventStore removeEvent:thisEvent span:EKSpanThisEvent error:&error];
                [self.tableView reloadData];
                break;

            default:
                break;
        }
        [controller dismissModalViewControllerAnimated:YES];
    }

    - (EKCalendar *)eventEditViewControllerDefaultCalendarForNewEvents:(EKEventEditViewController *)controller{
        EKCalendar *calendarForEdit=self.defaultCalendar;
        return calendarForEdit;
    }
    #pragma mark -
    #pragma mark Memory management

    - (void)didReceiveMemoryWarning {
        // Releases the view if it doesn't have a superview.
        [super didReceiveMemoryWarning];

        // Relinquish ownership any cached data, images, etc that aren't in use.
    }

    - (void)viewDidUnload {
        // Relinquish ownership of anything that can be recreated in viewDidLoad or on demand.
        // For example: self.myOutlet = nil;
        self.eventsList = nil;
        [self.detailViewController release];

    }


    - (void)dealloc {
        [super dealloc];
    }

This is what i did.... Help me out.

@thanks in advance.

Please do the following steps:

1) Press Build and Debug (Build -> Build and Debug - Breakpoints on) 2) Open your Debugger 3) Create the crash 4) Now, go to the debugger and search for a black item on the left side 5) Press this item and you'll find where the app is crashing

If you have done this, please write where your application crashs - this will be much easier. And maybe, you'll find the error.

I think your problem could be the self.navigationController.delegate = self; in -[EventViewController viewDidLoad]. When you hit the back button, the EventViewController is released, but the navigationController still thinks it is its delegate. Therefore, when it asks if it is OK to open the next view controller, it is calling methods on a released object and causing a crash.