视图被销毁时CoreData泄漏

Question

我正在尝试完成一个应用程序，但当我从导航堆栈中删除视图时，CoreData 出现了一些内存泄漏，即使我释放了我创建的所有内容。

下面的视图基本上会调用下面的方法。

+ (NSMutableArray *)getStoriesForSubscription:(Subscriptions *)s {
NSFetchRequest *request = [[NSFetchRequest alloc] init];
NSEntityDescription *storiesEntity = [NSEntityDescription entityForName:@"Articles" inManagedObjectContext:ikub.context];
[request setEntity:storiesEntity];
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"(belongsTo == %@)", s];
[request setPredicate:predicate];
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"pubDate" ascending:NO selector:nil];
NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor, nil];
[request setSortDescriptors:sortDescriptors]; 
NSError *error = nil;

NSMutableArray *stories = (NSMutableArray*)[ikub.context executeFetchRequest:request error:&error];
if (![ikub.context save:&error]) { NSLog(@"Cannot fetch the folders from the fetch request."); }
[sortDescriptors release];
[sortDescriptor release];
[request release];
return stories;
}


@implementation SubscriptionStories

@synthesize storiesTable, stories, subscription;

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

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
 UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"cell"];
  if (cell == nil) {
  cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:@"cell"];
 }
 int index = [indexPath row];
 cell.textLabel.text   = [[stories objectAtIndex:index] title];
 cell.detailTextLabel.text = [[stories objectAtIndex:index] desc];
 cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator;


 if ([[[stories objectAtIndex:index] read] isEqualToNumber:[NSNumber numberWithBool:NO]]) {
 cell.textLabel.textColor = [UIColor blackColor];
 } else {
 cell.textLabel.textColor = [UIColor grayColor];
 }

 return cell;
}

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
 StoryDetails *details = [[StoryDetails alloc] init];
 details.title = @"Detaje";
 details.t = [[stories objectAtIndex:[indexPath row]] title];
 details.d = [[stories objectAtIndex:[indexPath row]] desc];
 details.l = [[stories objectAtIndex:[indexPath row]] link];
 details.g = [[stories objectAtIndex:[indexPath row]] guid];
 details.p = (NSString *)[[stories objectAtIndex:[indexPath row]] pubDate];
 [SubscriptionsController setStoryAsRead:[[stories objectAtIndex:[indexPath row]] link] forSubscription:subscription];
 [self.navigationController pushViewController:details animated:YES];
 [details release];
}

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

- (void)viewWillAppear:(BOOL)animated {
stories = [[SubscriptionsController getStoriesForSubscription:subscription] retain];
[storiesTable reloadData];
}

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

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

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

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

仪器说泄漏发生在这一行：

stories = [[SubscriptionsController getStoriesForSubscription:subscription] retain];

Answer 1

如果你已经用retain声明了属性stories，那么额外的retain就没有必要了。

self.stories = [SubscriptionsController getStoriesForSubscription:subscription];

Answer 2

我的建议：

通过更改 UITableViewCell 创建以返回自动释放的单元格来删除（另一个？）泄漏

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    ...
        cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:@"cell"] autorelease];
    ...
}

如果这没有帮助。 （我有泄漏是仪器距离实际泄漏数英里）。将您的 viewWillDisappear 方法更改为这样的方法

- (void)viewWillDisappear:(BOOL)animated {
    [super viewWillDisappear:animated];
    [stories release];
    stories = nil;
}

并在 dealloc 中为故事添加另一个版本

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

也许在不调用 viewWillDisappear: 方法的情况下发生 dealloc 的方式很模糊。
我通常在 dealloc 中释放所有内容。只要确保在以另一种方法释放对象时将对象设置为 nil，就不会发生任何不好的事情。

Answer 3

泄漏发生在完全不同的地方。仪器并不总是正确的。