ios – CRASH尝试删除并重新加载相同的索引路径

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CollectionViewController.m line 439
__50-[CollectionViewController photoLibraryDidChange:]_block_invoke

致命异常：NSInternalInconsistencyException
尝试删除并重新加载相同的索引路径({length = 2,path = 0 – 26007})

  1. - (void)photoLibraryDidChange:(PHChange *)changeInstance
  2. {
  3.     // Call might come on any background queue. Re-dispatch to the main queue to handle it.
  4.     dispatch_async(dispatch_get_main_queue(),^{
  5.  
  6.         // check if there are changes to the assets (insertions,deletions,updates)
  7.         PHFetchResultChangeDetails *collectionChanges = [changeInstance changeDetailsForFetchResult:self.assetsFetchResults];
  8.         if (collectionChanges) {
  9.  
  10.             // get the new fetch result
  11.             self.assetsFetchResults = [collectionChanges fetchResultAfterChanges];
  12.  
  13.             UICollectionView *collectionView = self.collectionView;
  14.  
  15.             if (![collectionChanges hasIncrementalChanges] || [collectionChanges hasMoves]) {
  16.                 // we need to reload all if the incremental diffs are not available
  17.                 [collectionView reloadData];
  18.  
  19.             } else {
  20.                 // if we have incremental diffs,tell the collection view to animate insertions and deletions
  21.                 [collectionView performBatchUpdates:^{
  22.                     NSIndexSet *removedIndexes = [collectionChanges removedIndexes];
  23.                     if ([removedIndexes count]) {
  24.                         [collectionView deleteItemsAtIndexPaths:[removedIndexes aapl_indexPathsFromIndexesWithSection:0]];
  25.                     }
  26.                     NSIndexSet *insertedIndexes = [collectionChanges insertedIndexes];
  27.                     if ([insertedIndexes count]) {
  28.                         [collectionView insertItemsAtIndexPaths:[insertedIndexes aapl_indexPathsFromIndexesWithSection:0]];
  29.                     }
  30.                     NSIndexSet *changedIndexes = [collectionChanges changedIndexes];
  31.                     if ([changedIndexes count]) {
  32.                         [collectionView reloadItemsAtIndexPaths:[changedIndexes aapl_indexPathsFromIndexesWithSection:0]];
  33.                     }
  34.                 } completion:NULL];
  35.             }
  36.  
  37.             [self resetCachedAssets];
  38.         }
  39.     });
  40. }

来源：https://developer.apple.com/devcenter/download.action?path=/wwdc_2014/wwdc_2014_sample_code/exampleappusingphotosframework.zip

我无法复制这个问题.可能是什么问题呢？非常感谢！

解决方法

我今天能够再现这个.为此,您需要：

>打开正在监听更改的应用程序
>打开照片应用程序,将一组照片从iCloud共享相册保存到您的照片库
>转到照片应用程序,删除其中的一些照片
>再次转到iCloud共享相册,并再次保存您删除的一些照片.你会看到这种情况发生.

我发现一个更新的代码似乎在这里更好地处理更新行为：
https://developer.apple.com/library/ios/documentation/Photos/Reference/PHPhotoLibraryChangeObserver_Protocol/

但是它仍然不会处理这种情况,也不会在要删除的索引更大时(即由于未捕获的异常’NSInternalInconsistencyException’终止应用程序),原因是：尝试从第0部分删除第9项,其中只包含9个更新前的项目).我创建了这个代码更新版本,处理这个更好,迄今为止还没有为我崩溃.

  1. func photoLibraryDidChange(changeInfo: PHChange!) {
  2.  
  3.     // Photos may call this method on a background queue;
  4.     // switch to the main queue to update the UI.
  5.     dispatch_async(dispatch_get_main_queue()) {
  6.  
  7.  
  8.         // Check for changes to the list of assets (insertions,moves,or updates).
  9.         if let collectionChanges = changeInfo.changeDetailsForFetchResult(self.assetsFetchResult) {
  10.  
  11.             // Get the new fetch result for future change tracking.
  12.             self.assetsFetchResult = collectionChanges.fetchResultAfterChanges
  13.  
  14.             if collectionChanges.hasIncrementalChanges {
  15.  
  16.                 // Get the changes as lists of index paths for updating the UI.
  17.                 var removedPaths: [NSIndexPath]?
  18.                 var insertedPaths: [NSIndexPath]?
  19.                 var changedPaths: [NSIndexPath]?
  20.                 if let removed = collectionChanges.removedIndexes {
  21.                     removedPaths = self.indexPathsFromIndexSetWithSection(removed,section: 0)
  22.                 }
  23.                 if let inserted = collectionChanges.insertedIndexes {
  24.                     insertedPaths = self.indexPathsFromIndexSetWithSection(inserted,section: 0)
  25.                 }
  26.                 if let changed = collectionChanges.changedIndexes {
  27.                     changedPaths = self.indexPathsFromIndexSetWithSection(changed,section: 0)
  28.                 }
  29.                 var shouldReload = false
  30.                 if changedPaths != nil && removedPaths != nil{
  31.                     for changedPath in changedPaths!{
  32.                         if contains(removedPaths!,changedPath){
  33.                             shouldReload = true
  34.                             break
  35.                         }
  36.                     }
  37.  
  38.                 }
  39.  
  40.                 if removedPaths?.last?.item >= self.assetsFetchResult.count{
  41.                     shouldReload = true
  42.                 }
  43.  
  44.                 if shouldReload{
  45.                     self.collectionView.reloadData()
  46.                 }else{
  47.                     // Tell the collection view to animate insertions/deletions/moves
  48.                     // and to refresh any cells that have changed content.
  49.                     self.collectionView.performBatchUpdates(
  50.                         {
  51.                             if let theRemovedPaths = removedPaths {
  52.                                 self.collectionView.deleteItemsAtIndexPaths(theRemovedPaths)
  53.                             }
  54.                             if let theInsertedPaths = insertedPaths {
  55.                                 self.collectionView.insertItemsAtIndexPaths(theInsertedPaths)
  56.                             }
  57.                             if let theChangedPaths = changedPaths{
  58.                                 self.collectionView.reloadItemsAtIndexPaths(theChangedPaths)
  59.                             }
  60.                             if (collectionChanges.hasMoves) {
  61.                                 collectionChanges.enumerateMovesWithBlock() { fromIndex,toIndex in
  62.                                     let fromIndexPath = NSIndexPath(forItem: fromIndex,inSection: 0)
  63.                                     let toIndexPath = NSIndexPath(forItem: toIndex,inSection: 0)
  64.                                     self.collectionView.moveItemAtIndexPath(fromIndexPath,toIndexPath: toIndexPath)
  65.                                 }
  66.                             }
  67.                         },completion: nil)
  68.  
  69.                 }
  70.  
  71.             } else {
  72.                 // Detailed change information is not available;
  73.                 // repopulate the UI from the current fetch result.
  74.                 self.collectionView.reloadData()
  75.             }
  76.         }
  77.     }
  78. }
  79.  
  80. func indexPathsFromIndexSetWithSection(indexSet:NSIndexSet?,section:Int) -> [NSIndexPath]?{
  81.     if indexSet == nil{
  82.         return nil
  83.     }
  84.     var indexPaths:[NSIndexPath] = []
  85.  
  86.     indexSet?.enumerateIndexesUsingBlock { (index,Bool) -> Void in
  87.         indexPaths.append(NSIndexPath(forItem: index,inSection: section))
  88.     }
  89.     return indexPaths
  90.  
  91. }

Swift 3 / iOS 10版本：

  1. func photoLibraryDidChange(_ changeInstance: PHChange) {
  2.     guard let collectionView = self.collectionView else {
  3.         return
  4.     }
  5.  
  6.     // Photos may call this method on a background queue;
  7.     // switch to the main queue to update the UI.
  8.     DispatchQueue.main.async {
  9.         guard let fetchResults = self.fetchResults else {
  10.             collectionView.reloadData()
  11.             return
  12.         }
  13.  
  14.         // Check for changes to the list of assets (insertions,or updates).
  15.         if let collectionChanges = changeInstance.changeDetails(for: fetchResults) {
  16.             // Get the new fetch result for future change tracking.
  17.             self.fetchResults = collectionChanges.fetchResultAfterChanges
  18.  
  19.             if collectionChanges.hasIncrementalChanges {
  20.                 // Get the changes as lists of index paths for updating the UI.
  21.                 var removedPaths: [IndexPath]?
  22.                 var insertedPaths: [IndexPath]?
  23.                 var changedPaths: [IndexPath]?
  24.                 if let removed = collectionChanges.removedIndexes {
  25.                     removedPaths = self.indexPaths(from: removed,section: 0)
  26.                 }
  27.                 if let inserted = collectionChanges.insertedIndexes {
  28.                     insertedPaths = self.indexPaths(from:inserted,section: 0)
  29.                 }
  30.                 if let changed = collectionChanges.changedIndexes {
  31.                     changedPaths = self.indexPaths(from: changed,section: 0)
  32.                 }
  33.                 var shouldReload = false
  34.                 if let removedPaths = removedPaths,let changedPaths = changedPaths {
  35.                     for changedPath in changedPaths {
  36.                         if removedPaths.contains(changedPath) {
  37.                             shouldReload = true
  38.                             break
  39.                         }
  40.                     }
  41.                 }
  42.  
  43.                 if let item = removedPaths?.last?.item {
  44.                     if item >= fetchResults.count {
  45.                         shouldReload = true
  46.                     }
  47.                 }
  48.  
  49.                 if shouldReload {
  50.                     collectionView.reloadData()
  51.                 } else {
  52.                     // Tell the collection view to animate insertions/deletions/moves
  53.                     // and to refresh any cells that have changed content.
  54.                     collectionView.performBatchUpdates({
  55.                         if let theRemovedPaths = removedPaths {
  56.                             collectionView.deleteItems(at: theRemovedPaths)
  57.                         }
  58.                         if let theInsertedPaths = insertedPaths {
  59.                             collectionView.insertItems(at: theInsertedPaths)
  60.                         }
  61.                         if let theChangedPaths = changedPaths {
  62.                             collectionView.reloadItems(at: theChangedPaths)
  63.                         }
  64.  
  65.                         collectionChanges.enumerateMoves { fromIndex,toIndex in
  66.                             collectionView.moveItem(at: IndexPath(item: fromIndex,section: 0),to: IndexPath(item: toIndex,section: 0))
  67.                         }
  68.                     })
  69.                 }
  70.             } else {
  71.                 // Detailed change information is not available;
  72.                 // repopulate the UI from the current fetch result.
  73.                 collectionView.reloadData()
  74.             }
  75.         }
  76.     }
  77. }
  78.  
  79. func indexPaths(from indexSet: IndexSet?,section: Int) -> [IndexPath]? {
  80.     guard let set = indexSet else {
  81.         return nil
  82.     }
  83.  
  84.     return set.map { (index) -> IndexPath in
  85.         return IndexPath(item: index,section: section)
  86.     }
  87. }

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