Created
February 4, 2015 13:01
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UICollectionView w/ NSFetchedResultsController & NSBlockOperation. Idea originated from Blake Watters (https://github.com/AshFurrow/UICollectionView-NSFetchedResultsController/issues/13) Swift Version
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| func controllerWillChangeContent(controller: NSFetchedResultsController) { | |
| self.shouldReloadCollectionView = false | |
| self.blockOperation = NSBlockOperation() | |
| } | |
| func controller(controller: NSFetchedResultsController, didChangeSection sectionInfo: NSFetchedResultsSectionInfo, atIndex sectionIndex: Int, forChangeType type: NSFetchedResultsChangeType) { | |
| let collectionView = self.collectionView | |
| switch type { | |
| case NSFetchedResultsChangeType.Insert: | |
| self.blockOperation.addExecutionBlock({ | |
| collectionView.insertSections( NSIndexSet(index: sectionIndex) ) | |
| }) | |
| case NSFetchedResultsChangeType.Delete: | |
| self.blockOperation.addExecutionBlock({ | |
| collectionView.deleteSections( NSIndexSet(index: sectionIndex) ) | |
| }) | |
| case NSFetchedResultsChangeType.Update: | |
| self.blockOperation.addExecutionBlock({ | |
| collectionView.reloadSections( NSIndexSet(index: sectionIndex ) ) | |
| }) | |
| default:() | |
| } | |
| } | |
| func controller(controller: NSFetchedResultsController, didChangeObject anObject: AnyObject, atIndexPath indexPath: NSIndexPath?, forChangeType type: NSFetchedResultsChangeType, newIndexPath: NSIndexPath?) { | |
| let collectionView = self.collectionView | |
| switch type { | |
| case NSFetchedResultsChangeType.Insert: | |
| if collectionView.numberOfSections() > 0 { | |
| if collectionView.numberOfItemsInSection( newIndexPath!.section ) == 0 { | |
| self.shouldReloadCollectionView = true | |
| } else { | |
| self.blockOperation.addExecutionBlock({ | |
| collectionView.insertItemsAtIndexPaths( [newIndexPath!] ) | |
| }) | |
| } | |
| } else { | |
| self.shouldReloadCollectionView = true | |
| } | |
| case NSFetchedResultsChangeType.Delete: | |
| if collectionView.numberOfItemsInSection( indexPath!.section ) == 1 { | |
| self.shouldReloadCollectionView = true | |
| } else { | |
| self.blockOperation.addExecutionBlock({ | |
| collectionView.deleteItemsAtIndexPaths( [indexPath!] ) | |
| }) | |
| } | |
| case NSFetchedResultsChangeType.Update: | |
| self.blockOperation.addExecutionBlock({ | |
| collectionView.reloadItemsAtIndexPaths( [indexPath!] ) | |
| }) | |
| case NSFetchedResultsChangeType.Move: | |
| self.blockOperation.addExecutionBlock({ | |
| collectionView.moveItemAtIndexPath( indexPath!, toIndexPath: newIndexPath! ) | |
| }) | |
| default:() | |
| } | |
| } | |
| func controllerDidChangeContent(controller: NSFetchedResultsController) { | |
| // Checks if we should reload the collection view to fix a bug @ http://openradar.appspot.com/12954582 | |
| if self.shouldReloadCollectionView { | |
| self.collectionView.reloadData() | |
| } else { | |
| self.collectionView.performBatchUpdates({ | |
| self.blockOperation.start() | |
| }, completion: nil ) | |
| } | |
| } |
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This is awesome.
I had to subclass NSBlockOperation to keep crashes out, though. Also seem to still be working out a few random issues.