Photos(PHFetchResultChangeDetails)

Photos(PHChange)

Photos(PHObjectChangeDetails)

Photos(PHFetchResultChangeDetails)

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PHFetchResultChangeDetails主要用于记录PHFetchResult的变动，这样可以同时判断多个数据是否有变动。

1 获取PHFetchResult

/// 变化前public var fetchResultBeforeChanges: PHFetchResult { get }/// 变化后public var fetchResultAfterChanges: PHFetchResult { get }

2 获取变动信息

/// 是否有变动public var hasIncrementalChanges: Bool { get }/// 删除对象的位置public var removedIndexes: NSIndexSet? { get }/// 删除的对象public var removedObjects: [PHObject] { get }/// 插入对象的位置public var insertedIndexes: NSIndexSet? { get }/// 插入的对象public var insertedObjects: [PHObject] { get }/// 有变化的对象位置public var changedIndexes: NSIndexSet? { get }/// 有变化的对象public var changedObjects: [PHObject] { get }/// 移动照片public func enumerateMovesWithBlock(handler: (Int, Int) -> Void)/// 是否有移动public var hasMoves: Bool { get }

3 比较PHFetchResult

/// 获取两个PHFetchResult的差异////// - parameter fromResult : PHFetchResult/// - parameter toResult : PHFetchResult/// - parameter changedObjects : [PHObject]////// - returns: PHFetchResultChangeDetailspublic convenience init(fromFetchResult fromResult: PHFetchResult, toFetchResult toResult: PHFetchResult, changedObjects: [PHObject])

4 实战演练

func photoLibraryDidChange(changeInfo: PHChange!) {    // Photos may call this method on a background queue;    // switch to the main queue to update the UI.    dispatch_async(dispatch_get_main_queue()) {        // Check for changes to the displayed album itself        // (its existence and metadata, not its member assets).        if let albumChanges = changeInfo.changeDetailsForObject(self.displayedAlbum) {            // Fetch the new album and update the UI accordingly.            self.displayedAlbum = albumChanges.objectAfterChanges as PHAssetCollection            self.navigationController.navigationItem.title = self.displayedAlbum.localizedTitle        }        // Check for changes to the list of assets (insertions, deletions, moves, or updates).        if let collectionChanges = changeInfo.changeDetailsForFetchResult(self.assetsFetchResults) {            // Get the new fetch result for future change tracking.            self.assetsFetchResults = collectionChanges.fetchResultAfterChanges            if collectionChanges.hasIncrementalChanges {                // Get the changes as lists of index paths for updating the UI.                var removedPaths: [NSIndexPath]?                var insertedPaths: [NSIndexPath]?                var changedPaths: [NSIndexPath]?                if let removed = collectionChanges.removedIndexes {                    removedPaths = self.indexPathsFromIndexSet(removed)                }                if let inserted = collectionChanges.insertedIndexes {                    insertedPaths = self.indexPathsFromIndexSet(inserted)                }                if let changed = collectionChanges.changedIndexes {                    changedPaths = self.indexPathsFromIndexSet(changed)                }                // Tell the collection view to animate insertions/deletions/moves                // and to refresh any cells that have changed content.                self.collectionView.performBatchUpdates(                    {                        if removedPaths {                            self.collectionView.deleteItemsAtIndexPaths(removedPaths)                        }                        if insertedPaths {                            self.collectionView.insertItemsAtIndexPaths(insertedPaths)                        }                        if changedPaths {                            self.collectionView.reloadItemsAtIndexPaths(changedPaths)                        }                        if (collectionChanges.hasMoves) {                            collectionChanges.enumerateMovesWithBlock() { fromIndex, toIndex in                                let fromIndexPath = NSIndexPath(forItem: fromIndex, inSection: 0)                                let toIndexPath = NSIndexPath(forItem: toIndex, inSection: 0)                                self.collectionView.moveItemAtIndexPath(fromIndexPath, toIndexPath: toIndexPath)                            }                        }                    }, completion: nil)            } else {                // Detailed change information is not available;                // repopulate the UI from the current fetch result.                self.collectionView.reloadData()            }        }    }}

 

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其他

源代码

Swift

参考资料

Photos Framework Reference

PHChange Class Reference

PHFetchResultChangeDetails Class Reference

文档修改记录

时间 描述 2016-01-06 博文完成

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CSDN：http://blog.csdn.net/y550918116j

GitHub：https://github.com/937447974/Blog