获得与释放实例相关的崩溃

Question

我在 dealloc 中的 [selectedSession release]; 行遇到了崩溃：

Default [NSCheapMutableString release]: message sent to deallocated instance

我不明白为什么放入 dealloc 不正常？

以下所有当前代码：

LogViewController

    @implementation LogViewController

    @synthesize fetchedResultsController = __fetchedResultsController;
    @synthesize managedObjectContext;
    @synthesize logArray;
    @synthesize logTableView;
    @synthesize imageView;
    @synthesize session;
    @synthesize selectedSession;

    - (void)dealloc
    {
        [logArray release];
        [logTableView release];
        [session release];
        [__fetchedResultsController release];
        [managedObjectContext release];
        [imageView release];
        [selectedSession release];
        [super dealloc];
    }

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

    #pragma mark - View lifecycle

    - (void)viewDidLoad
    {
        self.logTableView.rowHeight = 47;
        [super viewDidLoad];
        self.navigationItem.title = @"Log";
        logTableView.backgroundColor = [UIColor clearColor];
        logTableView.separatorColor = [UIColor grayColor];
        self.navigationController.navigationBar.tintColor = [UIColor colorWithRed:24/255.0 green:83/255.0 blue:170/255.0 alpha:1.0];
        self.logArray = [[NSArray alloc]initWithObjects:@"Today", @"Previous", @"Past Week", @"Past Month", @"All Workouts", nil];

        if (managedObjectContext == nil) 
        { 
            self.managedObjectContext = [(CurlAppDelegate *)[[UIApplication sharedApplication] delegate] managedObjectContext]; 
        }
    }

    - (void)viewDidUnload
    {
        self.logTableView = nil;
        self.fetchedResultsController = nil;
        self.imageView = nil;
        self.managedObjectContext = nil;
        [super viewDidUnload];
    }

    - (void)viewDidAppear:(BOOL)animated
    {
        [super viewDidAppear:animated];
    }

    - (void)viewWillDisappear:(BOOL)animated
    {
        [super viewWillDisappear:animated];
    }

    - (void)viewDidDisappear:(BOOL)animated
    {
        [super viewDidDisappear:animated];
    }

    - (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
    {
        // Return YES for supported orientations
        return (interfaceOrientation == UIInterfaceOrientationPortrait);
    }

    #pragma mark - Table view data source


    - (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
    {
        return 1;
    }

    - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
    {
        return [self.logArray count];
    }

    - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
    {
        static NSString *CellIdentifier = @"Cell";
        TDBadgedCell *cell = [[[TDBadgedCell alloc] initWithStyle:UITableViewCellStyleValue1 reuseIdentifier:CellIdentifier] autorelease];
        [self configureCell:cell atIndexPath:indexPath];
        return cell;
    }

    - (void)configureCell:(TDBadgedCell *)cell atIndexPath:(NSIndexPath *)indexPath
    {
        cell.textLabel.textColor = [UIColor blackColor];
        cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator;
        cell.textLabel.text = [logArray objectAtIndex:indexPath.row];
        cell.backgroundColor = [UIColor clearColor];
        cell.imageView.image = [UIImage imageNamed:@"17-bar-chart.png"];
        UIImageView *myImageView = nil;
        myImageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"silvercell5.png"]];
        [cell setBackgroundView:myImageView]; 
        [myImageView release];

        NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init]; 
        [dateFormatter setDateFormat:@"MMM d, y"]; 
        NSDate *date = nil;
        if (indexPath.row == 0)
        {
            date = [NSDate date]; 
            NSString *dateString = [dateFormatter stringFromDate:date]; 
            cell.badgeString = dateString;
        }
        else if (indexPath.row == 1)
        {
            if ([[self.fetchedResultsController fetchedObjects]count] > 1)
            {
                self.session = [[self.fetchedResultsController fetchedObjects]objectAtIndex:1];
                NSDate *date = self.session.timeStamp;
                NSString *dateString = [dateFormatter stringFromDate:date]; 
                cell.badgeString = dateString;
            }
            else
            {
                cell.badgeString = @"None";
            }
        }
        else if (indexPath.row > 1)
        {
            cell.badgeString = [NSString stringWithFormat:@"%i", [[self.fetchedResultsController fetchedObjects]count]];
        }
        cell.badgeColor = [UIColor colorWithRed:24/255.0 green:83/255.0 blue:170/255.0 alpha:1.0];
        [dateFormatter release]; 
    }

    #pragma mark - Table view delegate

    - (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
    {    
        [tableView deselectRowAtIndexPath:indexPath animated:YES];

        if (indexPath.row == 0 || indexPath.row == 1)
        {
            SessionViewController *detailViewController = [[SessionViewController alloc] initWithNibName:@"SessionViewController" bundle:nil];
            detailViewController.title = [logArray objectAtIndex: indexPath.row];
            self.selectedSession = (Session *)[__fetchedResultsController objectAtIndexPath:indexPath];
            detailViewController.selectedSession = self.selectedSession;
            NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init]; 
            [dateFormatter setDateFormat:@"MMM d, y"]; 
            NSString *dateString = [dateFormatter stringFromDate:selectedSession.timeStamp]; 
            detailViewController.title = dateString;
            [self.navigationController pushViewController:detailViewController animated:YES];
            [detailViewController release];
            [dateFormatter release];
        }
        else
        {
            LogResultsViewController *detailViewController = [[LogResultsViewController alloc] initWithNibName:@"LogResultsTableViewController" bundle:nil];
            detailViewController.title = [logArray objectAtIndex: indexPath.row];
            [self.navigationController pushViewController:detailViewController animated:YES];
            [detailViewController release];   
        }
    }
#pragma mark - Fetched results controller

- (NSFetchedResultsController *)fetchedResultsController
{
    if (fetchedResultsController != nil)
    {
        return fetchedResultsController;
    }

    // Create the fetch request for the entity.
    NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
    // Edit the entity name as appropriate.
    NSEntityDescription *entity = [NSEntityDescription entityForName:@"Session" inManagedObjectContext:self.managedObjectContext];
    [fetchRequest setEntity:entity];

    NSIndexPath *indexPath = [NSIndexPath indexPathForRow:0 inSection:0] ;
    NSDate *today = [NSDate date]; 
    NSDate *thisWeek  = [today dateByAddingTimeInterval: -604800.0];
    NSDate *thisMonth = [today dateByAddingTimeInterval: -2629743.83]; // Use NSCalendar for

    if (indexPath.row ==2)
    {
        [fetchRequest setPredicate:[NSPredicate predicateWithFormat:@"(date >= %@) AND (date <= %@)", thisWeek, today]];
    }
    else if (indexPath.row ==3)
    {
        [fetchRequest setPredicate:[NSPredicate predicateWithFormat:@"(date >= %@) AND (date <= %@)", thisMonth, today]];
    }

    // Set the batch size to a suitable number.
    [fetchRequest setFetchBatchSize:20];

    // Edit the sort key as appropriate.
    NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"timeStamp" ascending:NO];
    NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor, nil];

    [fetchRequest setSortDescriptors:sortDescriptors];

    // Edit the section name key path and cache name if appropriate.
    // nil for section name key path means "no sections".
    NSFetchedResultsController *aFetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:self.managedObjectContext sectionNameKeyPath:nil cacheName:nil];
    aFetchedResultsController.delegate = self;
    self.fetchedResultsController = aFetchedResultsController;

    [aFetchedResultsController release];
    [fetchRequest release];
    [sortDescriptor release];
    [sortDescriptors release];

    NSError *error = nil;
    if (![self.fetchedResultsController performFetch:&error])
    {
        /*
         Replace this implementation with code to handle the error appropriately.

         abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development. If it is not possible to recover from the error, display an alert panel that instructs the user to quit the application by pressing the Home button.
         */
        NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
        abort();
    }
    NSLog(@"Number of Objects = %i",
           [[fetchedResultsController fetchedObjects] count]);
    return fetchedResultsController;
    NSLog(@"Number of Objects = %i",
          [[fetchedResultsController fetchedObjects] count]);

}    

#pragma mark - Fetched results controller delegate


- (void)controllerWillChangeContent:(NSFetchedResultsController *)controller
{
    [self.logTableView beginUpdates];
}

- (void)controller:(NSFetchedResultsController *)controller didChangeSection:(id <NSFetchedResultsSectionInfo>)sectionInfo
           atIndex:(NSUInteger)sectionIndex forChangeType:(NSFetchedResultsChangeType)type
{
    switch(type)
    {
        case NSFetchedResultsChangeInsert:
            [self.logTableView insertSections:[NSIndexSet indexSetWithIndex:sectionIndex] withRowAnimation:UITableViewRowAnimationFade];
            break;

        case NSFetchedResultsChangeDelete:
            [self.logTableView deleteSections:[NSIndexSet indexSetWithIndex:sectionIndex] withRowAnimation:UITableViewRowAnimationFade];
            break;
    }
}

- (void)controller:(NSFetchedResultsController *)controller didChangeObject:(id)anObject
       atIndexPath:(NSIndexPath *)indexPath forChangeType:(NSFetchedResultsChangeType)type
      newIndexPath:(NSIndexPath *)newIndexPath
{
    UITableView *tableView = self.logTableView;

    switch(type)
    {

        case NSFetchedResultsChangeInsert:
            [tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath] withRowAnimation:UITableViewRowAnimationFade];
            break;

        case NSFetchedResultsChangeDelete:
            [tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
            break;

        case NSFetchedResultsChangeUpdate:
            [self configureCell:[tableView cellForRowAtIndexPath:indexPath] atIndexPath:indexPath];
            break;

        case NSFetchedResultsChangeMove:
            [tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
            [tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath]withRowAnimation:UITableViewRowAnimationFade];
            break;
    }
}

- (void)controllerDidChangeContent:(NSFetchedResultsController *)controller
{
    [self.logTableView endUpdates];
}

LogResultsViewController

    @implementation LogResultsViewController
    @synthesize fetchedResultsController = __fetchedResultsController;
    @synthesize managedObjectContext;
    @synthesize resultsTableView;
    @synthesize selectedSession;

    - (void)dealloc
    {
        [__fetchedResultsController release];
        [managedObjectContext release];
        [selectedSession release];
        [resultsTableView release];
        [super dealloc];
    }

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

    #pragma mark - View lifecycle

    - (void)viewDidLoad
    {
        [super viewDidLoad];

        self.resultsTableView.separatorColor = [UIColor grayColor];

        self.resultsTableView.rowHeight = 50;

        [self managedObjectContext];
    }

    - (NSManagedObjectContext *)managedObjectContext 
    {
        if (managedObjectContext != nil) 
        {
            return managedObjectContext;
        }
        NSPersistentStoreCoordinator *coordinator = [(CurlAppDelegate *)[[UIApplication sharedApplication] delegate] persistentStoreCoordinator];   
        if (coordinator != nil) 
        {
            managedObjectContext = [[NSManagedObjectContext alloc] init];
            [managedObjectContext setPersistentStoreCoordinator:coordinator];
        }
        return managedObjectContext;
    }

    - (void)viewDidUnload
    {
        [super viewDidUnload];
        self.managedObjectContext = nil;
        self.fetchedResultsController = nil;
        self.resultsTableView = nil;
    }

    #pragma mark - Table view data source

    - (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
    {
        return 1;
    }

    - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
    {
        id <NSFetchedResultsSectionInfo> sectionInfo = [[self.fetchedResultsController sections] objectAtIndex:section];
        return [sectionInfo numberOfObjects];
    }

    - (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];
        }    
        [self configureCell:cell atIndexPath:indexPath];
        return cell;
    }

    - (void)configureCell:(UITableViewCell *)cell atIndexPath:(NSIndexPath *)indexPath
    {
        Session *session = (Session *)[__fetchedResultsController objectAtIndexPath:indexPath];
        NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init]; 
        [dateFormatter setDateFormat:@"eeee, MMM d, y"]; 
        NSString *dateString = [dateFormatter stringFromDate:session.timeStamp]; 

        NSDate *lastDate = session.timeStamp;
        NSDate *todaysDate = [NSDate date];
        NSTimeInterval lastDiff = [lastDate timeIntervalSinceNow];
        NSTimeInterval todaysDiff = [todaysDate timeIntervalSinceNow];
        NSTimeInterval dateDiff = todaysDiff-lastDiff;
        NSTimeInterval dayDifference = dateDiff/86400;
        int days = (int) dayDifference;
        NSLog(@"%i days",days);

        cell.textLabel.text = dateString;
        cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator;
        cell.detailTextLabel.text = [NSString stringWithFormat: @"%i days ago", days];
        cell.detailTextLabel.textColor = [UIColor colorWithRed:24/255.0 green:83/255.0 blue:170/255.0 alpha:1.0];
        cell.imageView.image = [UIImage imageNamed:@"11-clock.png"];
        self.resultsTableView.tableFooterView = [[[UIView alloc] init] autorelease];

        UIImageView *myImageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"silvercell3.png"]];
        [cell setBackgroundView:myImageView];
        [dateFormatter release];
        [myImageView release];
    }

    -(void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath
    {
        if (editingStyle == UITableViewCellEditingStyleDelete) 
        {
            // Delete the managed object for the given index path
            NSManagedObjectContext *context = [__fetchedResultsController managedObjectContext];
            [context deleteObject:[__fetchedResultsController objectAtIndexPath:indexPath]];

            // Commit the change.
            NSError *error = nil;

            // Update the array and table view.
            if (![managedObjectContext save:&error]) 
            {
                // Handle the error.
            }
            //[tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:YES];
        }
    }

    // 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;
    }

    #pragma mark - Table view delegate

    - (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
    {
        SessionViewController *sessionViewController = [[SessionViewController alloc] initWithNibName:@"SessionViewController" bundle:nil];
        selectedSession = (Session *)[__fetchedResultsController objectAtIndexPath:indexPath];
        sessionViewController.selectedSession = self.selectedSession;
        NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init]; 
        [dateFormatter setDateFormat:@"MMM d, y"]; 
        NSString *dateString = [dateFormatter stringFromDate:selectedSession.timeStamp]; 
        sessionViewController.title = dateString;

        [self.navigationController pushViewController:sessionViewController animated:YES];
        [sessionViewController release];
        [dateFormatter release];
    }
#pragma mark - Fetched results controller

- (NSFetchedResultsController *)fetchedResultsController
{
    if (fetchedResultsController != nil)
    {
        return fetchedResultsController;
    }

    // Create the fetch request for the entity.
    NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
    // Edit the entity name as appropriate.
    NSEntityDescription *entity = [NSEntityDescription entityForName:@"Session" inManagedObjectContext:self.managedObjectContext];
    [fetchRequest setEntity:entity];


    // Set the batch size to a suitable number.
    [fetchRequest setFetchBatchSize:20];

    // Edit the sort key as appropriate.
    NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"timeStamp" ascending:NO];
    NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor, nil];

    [fetchRequest setSortDescriptors:sortDescriptors];

    // Edit the section name key path and cache name if appropriate.
    // nil for section name key path means "no sections".
    NSFetchedResultsController *aFetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:self.managedObjectContext sectionNameKeyPath:nil cacheName:nil];
    aFetchedResultsController.delegate = self;
    self.fetchedResultsController = aFetchedResultsController;

    [aFetchedResultsController release];
    [fetchRequest release];
    [sortDescriptor release];
    [sortDescriptors release];

    NSError *error = nil;
    if (![fetchedResultsController performFetch:&error])
    {
        /*
         Replace this implementation with code to handle the error appropriately.

         abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development. If it is not possible to recover from the error, display an alert panel that instructs the user to quit the application by pressing the Home button.
         */
        NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
        abort();
    }
    return fetchedResultsController;
}    

#pragma mark - Fetched results controller delegate


- (void)controllerWillChangeContent:(NSFetchedResultsController *)controller
{
    [self.resultsTableView beginUpdates];
}

- (void)controller:(NSFetchedResultsController *)controller didChangeSection:(id <NSFetchedResultsSectionInfo>)sectionInfo
           atIndex:(NSUInteger)sectionIndex forChangeType:(NSFetchedResultsChangeType)type
{
    switch(type)
    {
        case NSFetchedResultsChangeInsert:
            [self.resultsTableView insertSections:[NSIndexSet indexSetWithIndex:sectionIndex] withRowAnimation:UITableViewRowAnimationFade];
            break;

        case NSFetchedResultsChangeDelete:
            [self.resultsTableView deleteSections:[NSIndexSet indexSetWithIndex:sectionIndex] withRowAnimation:UITableViewRowAnimationFade];
            break;
    }
}

- (void)controller:(NSFetchedResultsController *)controller didChangeObject:(id)anObject
       atIndexPath:(NSIndexPath *)indexPath forChangeType:(NSFetchedResultsChangeType)type
      newIndexPath:(NSIndexPath *)newIndexPath
{
    UITableView *tableView = self.resultsTableView;

    switch(type)
    {

        case NSFetchedResultsChangeInsert:
            [tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath] withRowAnimation:UITableViewRowAnimationFade];
            break;

        case NSFetchedResultsChangeDelete:
            [tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
            break;

        case NSFetchedResultsChangeUpdate:
            [self configureCell:[tableView cellForRowAtIndexPath:indexPath] atIndexPath:indexPath];
            break;

        case NSFetchedResultsChangeMove:
            [tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
            [tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath]withRowAnimation:UITableViewRowAnimationFade];
            break;
    }
}

- (void)controllerDidChangeContent:(NSFetchedResultsController *)controller
{
    [self.resultsTableView endUpdates];
}

SessionViewController

@implementation SessionViewController

@synthesize exerciseArray;
@synthesize selectedSession;

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

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

-(IBAction)showActionSheet {
    UIActionSheet *actionSheet = [[UIActionSheet alloc] initWithTitle:@"Share" delegate:self cancelButtonTitle:@"Cancel" destructiveButtonTitle:nil otherButtonTitles:@"Twitter",@"Facebook",nil];
    [actionSheet showInView:self.tabBarController.view];
    [actionSheet release];
}

- (void)tweet
{
    SHKItem *aTweet = [SHKItem text:[NSString stringWithFormat: @"Twitter: testing 1,2,3."]];
    [SHKTwitter shareItem:aTweet];
}

- (void)facebook
{
    SHKItem *post = [SHKItem text: [NSString stringWithFormat: @"Facebook: testing 1,2,3."]];
//    post.URL = [NSURL URLWithString:@"http://sugarrush-app.com/"];
    [SHKFacebook shareItem:post];
} 

#pragma mark - View lifecycle

- (void)viewDidLoad
{
    [super viewDidLoad];
    UIBarButtonItem *actionButton = [[UIBarButtonItem alloc] initWithTitle:@"Share" style:UIBarButtonItemStylePlain target:self action:@selector(showActionSheet)];
    self.navigationItem.rightBarButtonItem = actionButton;
    [actionButton release];

    NSSet *exercises = [self.selectedSession valueForKey:@"exercises"];
    NSArray *sortDescriptors = [NSArray arrayWithObject:[NSSortDescriptor sortDescriptorWithKey:@"timeStamp" ascending:YES]];
    NSArray *sorted = [exercises sortedArrayUsingDescriptors:sortDescriptors];
    self.exerciseArray = sorted;
}

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

#pragma mark - Table view data source

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
    return 1;
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    return [exerciseArray count];
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString *CellIdentifier = @"Cell";
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
    if (cell == nil) {
        cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];
    }
    Exercise *exercise = (Exercise *)[exerciseArray objectAtIndex:indexPath.row];
    cell.textLabel.text = exercise.name;
    return cell;
}

@end

Answer 1

您应该在 viewDidUnload 中释放或设置为 nil 的唯一对象是按钮、标签、文本框等。

例如，当您执行 self.selectedSession = nil 时，它正在调用该方法的释放；这就是属性的重点，它们处理分配和释放。

Answer 2

您发布了一个 tableView:didSelectRowAtIndexPath:，但我认为您没有告诉我们这是在哪个类中。

无论如何，该方法似乎有一个错误：

selectedSession = (Session *)[__fetchedResultsController objectAtIndexPath:indexPath];
sessionViewController.selectedSession = self.selectedSession;

我认为在第一行，你的意思是说 self.selectedSession，假设你继续在这个类的 dealloc 中释放 selectedSession。 （这可能不是您唯一的问题）

编辑：

您应该在 viewDidUnload 中将属性设置为 nil，当且仅当这些属性是由于从您的 nib 加载视图而设置的，或者是在 loadView 或 viewDidLoad 中设置的。您这样做的原因是 viewDidLoad 或 loadView 在视图控制器的生命周期内可能会被多次调用。

编辑：

在设置 fetchedResultsController 时检查您是否正在使用该属性，并确保您没有在 viewDidUnload 上将其设置为 nil。

Answer 3

不要在 viewDidUnload 中将 selectedSession 和 exerciseArray 设置为 nil。

既然你这样做了，它会在你试图释放 nil 对象时在 dealloc 中崩溃。

另外，在释放数组之前，调用 [array removeAllObjects] 总是一个好主意。

Answer 4

在您的 viewDidLoad 方法中，您将 self.selectedSession 和 self.exerciseArray 设置为 nil。您应该只在 viewDidLoad 中将接口插座设置为 nil。但这不是您崩溃的原因，因为当您到达 dealloc 时，您只是将 release 发送到 nil。

您可能想查看 selectedSession 对象的内容。您可能在其中一个成员中过度释放 NSString