iphone - NSFetchedResultsController objectAtIndex 的内存泄漏

Question

我在使用 NSFetchedResultsController objectAtIndex 时出现内存泄漏:栈帧如下:

   0 CoreFoundation __CFDataAllocate
   1 CoreFoundation __CFDataInit
   2 CoreData -[NSSQLCore _prepareResultsFromResultSet:usingFetchPlan:withMatchingRows:]
   3 CoreData -[NSSQLCore _newRowsForFetchPlan:selectedBy:withArgument:]
   4 CoreData -[NSSQLCore newRowsForFetchPlan:]
   5 CoreData -[NSSQLCore objectsForFetchRequest:inContext:]
   6 CoreData -[NSSQLCore executeRequest:withContext:error:]
   7 CoreData -[NSPersistentStoreCoordinator executeRequest:withContext:error:]
   8 CoreData -[NSManagedObjectContext executeFetchRequest:error:]
   9 CoreData _faultBatchAtIndex
  10 CoreData -[_PFBatchFaultingArray objectAtIndex:]
  --->  11 MyApp -[DocumentViewController tableView:heightForRowAtIndexPath:] 
  12 UIKit -[UISectionRowData refreshWithSection:tableView:tableViewRowData:]
  13 UIKit -[UITableViewRowData rectForFooterInSection:]
  14 UIKit -[UITableViewRowData heightForTable]
  15 UIKit -[UITableView(_UITableViewPrivate) _updateContentSize]
  16 UIKit -[UITableView noteNumberOfRowsChanged]
  17 UIKit -[UITableView reloadData]
  18 UIKit -[UITableView layoutSubviews]
  19 QuartzCore -[CALayer layoutSublayers]
  20 QuartzCore CALayerLayoutIfNeeded
  21 QuartzCore CA::Context::commit_transaction(CA::Transaction*)
  22 QuartzCore CA::Transaction::commit()
  23 QuartzCore CA::Transaction::observer_callback(__CFRunLoopObserver*, unsigned long, void*)
  24 CoreFoundation __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__
  25 CoreFoundation __CFRunLoopDoObservers
  26 CoreFoundation __CFRunLoopRun
  27 CoreFoundation CFRunLoopRunSpecific
  28 CoreFoundation CFRunLoopRunInMode
  29 GraphicsServices GSEventRunModal
  30 GraphicsServices GSEventRun
  31 UIKit UIApplicationMain

从这个堆栈帧来看，使用 objectAtIndex 访问的对象似乎被泄漏了。

但是，当我离开 Controller 时，它的 dealloc 方法会被调用。在这个方法中，由于我使用了[NSManagedObjectContextfreshObject:mergeChange]，所以由fetchedresultscontroller获取的所有对象都会变成错误。

为了使我的描述更加完整，下面是创建泄漏对象的代码:

- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{
    Page* page = [[self fetchedResultsController] objectAtIndexPath:indexPath];
    UIImage* thumbnail = [page getThumbnail];
    [[self managedObjectContext] refreshObject:page.image mergeChanges:NO];
    CGFloat height = [PageCell cellImageSize:thumbnail].height + 20;
    return height;
}

任何提示将不胜感激，谢谢!

Answer 1

检查获取 UIImage 的代码。泄漏很可能就在那里。它的确切位置取决于您如何创建图像对象。