From d84970d2daf763f6a782c010ac9a9987f41d6c05 Mon Sep 17 00:00:00 2001
From: tilltue <tilltue@gmail.com>
Date: Sun, 3 Sep 2017 21:56:59 +0900
Subject: [PATCH] add PHPhotoLibraryChangeObserver - Fixes #24

---
 .../Classes/TLAssetsCollection.swift          |  2 ++
 TLPhotoPicker/Classes/TLPhotoLibrary.swift    | 13 +++++--
 .../TLPhotosPickerViewController.swift        | 36 ++++++++++++++++++-
 3 files changed, 48 insertions(+), 3 deletions(-)

diff --git a/TLPhotoPicker/Classes/TLAssetsCollection.swift b/TLPhotoPicker/Classes/TLAssetsCollection.swift
index 36c8b7aa..394c4429 100644
--- a/TLPhotoPicker/Classes/TLAssetsCollection.swift
+++ b/TLPhotoPicker/Classes/TLAssetsCollection.swift
@@ -59,6 +59,7 @@ extension TLPHAsset: Equatable {
 }
 
 struct TLAssetsCollection {
+    var phAssetCollection: PHAssetCollection? = nil
     var fetchResult: PHFetchResult<PHAsset>? = nil
     var thumbnail: UIImage? = nil
     var useCameraButton: Bool = false
@@ -73,6 +74,7 @@ struct TLAssetsCollection {
     }
     
     init(collection: PHAssetCollection) {
+        self.phAssetCollection = collection
         self.title = collection.localizedTitle ?? ""
         self.localIdentifier = collection.localIdentifier
     }
diff --git a/TLPhotoPicker/Classes/TLPhotoLibrary.swift b/TLPhotoPicker/Classes/TLPhotoLibrary.swift
index fbc47579..eb01bd47 100644
--- a/TLPhotoPicker/Classes/TLPhotoLibrary.swift
+++ b/TLPhotoPicker/Classes/TLPhotoLibrary.swift
@@ -111,11 +111,20 @@ class TLPhotoLibrary {
 
 //MARK: - Load Collection
 extension TLPhotoLibrary {
-    func fetchCollection(allowedVideo: Bool = true, useCameraButton: Bool = true, mediaType: PHAssetMediaType? = nil) {
-        
+    func getOption() -> PHFetchOptions {
         let options = PHFetchOptions()
         let sortOrder = [NSSortDescriptor(key: "creationDate", ascending: false)]
         options.sortDescriptors = sortOrder
+        return options
+    }
+    
+    func fetchResult(collection: TLAssetsCollection?) -> PHFetchResult<PHAsset>? {
+        guard let phAssetCollection = collection?.phAssetCollection else { return nil }
+        return PHAsset.fetchAssets(in: phAssetCollection, options: getOption())
+    }
+    
+    func fetchCollection(allowedVideo: Bool = true, useCameraButton: Bool = true, mediaType: PHAssetMediaType? = nil) {
+        let options = getOption()
         
         @discardableResult
         func getSmartAlbum(subType: PHAssetCollectionSubtype, result: inout [TLAssetsCollection]) -> TLAssetsCollection? {
diff --git a/TLPhotoPicker/Classes/TLPhotosPickerViewController.swift b/TLPhotoPicker/Classes/TLPhotosPickerViewController.swift
index 61054b98..bd3ac64d 100644
--- a/TLPhotoPicker/Classes/TLPhotosPickerViewController.swift
+++ b/TLPhotoPicker/Classes/TLPhotosPickerViewController.swift
@@ -121,6 +121,7 @@ open class TLPhotosPickerViewController: UIViewController {
     
     deinit {
         //print("deinit TLPhotosPickerViewController")
+        PHPhotoLibrary.shared().unregisterChangeObserver(self)
     }
     
     required public init?(coder aDecoder: NSCoder) {
@@ -267,6 +268,10 @@ extension TLPhotosPickerViewController {
         }
     }
     
+    fileprivate func registerChangeObserver() {
+        PHPhotoLibrary.shared().register(self)
+    }
+    
     fileprivate func getfocusedIndex() -> Int {
         guard let focused = self.focusedCollection, let result = self.collections.index(where: { $0 == focused }) else { return 0 }
         return result
@@ -398,6 +403,7 @@ extension TLPhotosPickerViewController: TLPhotoLibraryDelegate {
     func loadCompleteAllCollection(collections: [TLAssetsCollection]) {
         self.collections = collections
         self.reloadTableView()
+        self.registerChangeObserver()
     }
     
     func focusCollection(collection: TLAssetsCollection) {
@@ -523,8 +529,36 @@ extension TLPhotosPickerViewController: PHLivePhotoViewDelegate {
     }
 }
 
+// MARK: - PHPhotoLibraryChangeObserver
+extension TLPhotosPickerViewController: PHPhotoLibraryChangeObserver {
+    public func photoLibraryDidChange(_ changeInstance: PHChange) {
+        guard let changeFetchResult = self.focusedCollection?.fetchResult else { return }
+        guard let changes = changeInstance.changeDetails(for: changeFetchResult) else { return }
+        guard let fetchResult = self.photoLibrary.fetchResult(collection: self.focusedCollection) else { return }
+        let addIndex = self.usedCameraButton ? 1 : 0
+        DispatchQueue.main.sync {
+            if changes.hasIncrementalChanges {
+                self.collectionView.performBatchUpdates({ [weak self] _ in
+                    self?.focusedCollection?.fetchResult = fetchResult
+                    if let removed = changes.removedIndexes, removed.count > 0 {
+                        self?.collectionView.deleteItems(at: removed.map { IndexPath(item: $0+addIndex, section:0) })
+                    }
+                    if let inserted = changes.insertedIndexes, inserted.count > 0 {
+                        self?.collectionView.insertItems(at: inserted.map { IndexPath(item: $0+addIndex, section:0) })
+                    }
+                    if let changed = changes.changedIndexes, changed.count > 0 {
+                        self?.collectionView.reloadItems(at: changed.map { IndexPath(item: $0+addIndex, section:0) })
+                    }
+                })
+            }else {
+                self.focusedCollection?.fetchResult = fetchResult
+                self.collectionView.reloadData()
+            }
+        }
+    }
+}
 
-// UICollectionView delegate & datasource
+// MARK: - UICollectionView delegate & datasource
 extension TLPhotosPickerViewController: UICollectionViewDelegate,UICollectionViewDataSource,UICollectionViewDataSourcePrefetching {
     fileprivate func getSelectedAssets(_ asset: TLPHAsset) -> TLPHAsset? {
         if let index = self.selectedAssets.index(where: { $0.phAsset == asset.phAsset }) {