wip

Source/IGListAutoSectionController.h

@@ -0,0 +1,55 @@
+/**
+ * Copyright (c) 2016-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#import <UIKit/UIKit.h>
+
+#import <IGListKit/IGListMacros.h>
+#import <IGListKit/IGListSectionType.h>
+#import <IGListKit/IGListSectionController.h>
+
+@protocol IGListDiffable;
+@protocol IGListBindable;
+
+/**
+ Other naming options
+ 
+ - IGListDiffingSectionController
+ - IGListBindingSectionController
+ - IGListAutoSectionController
+ */
+
+NS_ASSUME_NONNULL_BEGIN
+
+@protocol IGListAutoSectionControllerDataSource <NSObject>
+
+- (NSArray<id<IGListDiffable>> *)viewModelsForObject:(id)object;
+- (UICollectionViewCell<IGListBindable> *)cellForViewModel:(id)viewModel atIndex:(NSInteger)index;
+- (CGSize)sizeForViewModel:(id)viewModel;
+
+@end
+
+@interface IGListAutoSectionController : IGListSectionController<IGListSectionType>
+
+/**
+ func transform(object: IGListDiffable) -> [IGListDiffable]
+ func cellClass(viewModel: IGListDiffable) -> Class (of type UICollectionView<IGListBindable>)
+ 
+ how to add "extra" stuff to the cell, e.g. delegates. options:
+ - override superclass method (don't call super tho)
+ - use IGListDisplayDelegate (adds lots of boilerplate)
+ - new, optional delegate w/ bindable method
+ */
+
+@property (nonatomic, weak, nullable) id<IGListAutoSectionControllerDataSource> dataSource;
+
+- (void)updateAnimated:(BOOL)animated completion:(nullable void (^)())completion;
+
+@end
+
+NS_ASSUME_NONNULL_END

Source/IGListAutoSectionController.m

@@ -0,0 +1,119 @@
+/**
+ * Copyright (c) 2016-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#import "IGListAutoSectionController.h"
+
+#import <IGListKit/IGListAssert.h>
+#import <IGListKit/IGListDiffable.h>
+#import <IGListKit/IGListDiff.h>
+#import <IGListKit/IGListBindable.h>
+
+typedef NS_ENUM(NSInteger, IGListAutoSectionState) {
+    IGListAutoSectionStateIdle = 0,
+    IGListAutoSectionStateUpdateQueued,
+    IGListAutoSectionStateUpdateApplied
+};
+
+@interface IGListAutoSectionController()
+
+@property (nonatomic, strong) id object;
+@property (nonatomic, strong) NSArray<id<IGListDiffable>> *viewModels;
+@property (nonatomic, assign) IGListAutoSectionState state;
+
+@end
+
+@implementation IGListAutoSectionController
+
+#pragma mark - Public API
+
+- (void)updateAnimated:(BOOL)animated completion:(void (^)())completion {
+    IGAssertMainThread();
+
+    if (self.state != IGListAutoSectionStateIdle) {
+        return;
+    }
+    self.state = IGListAutoSectionStateUpdateQueued;
+
+    __block IGListIndexSetResult *result = nil;
+    __block NSArray<id<IGListDiffable>> *oldViewModels = nil;
+
+    id<IGListCollectionContext> collectionContext = self.collectionContext;
+
+    [collectionContext performBatchAnimated:YES updates:^{
+        if (self.state != IGListAutoSectionStateUpdateQueued) {
+            return;
+        }
+
+        oldViewModels = self.viewModels;
+        self.viewModels = [self.dataSource viewModelsForObject:self.object];
+        result = IGListDiff(oldViewModels, self.viewModels, IGListDiffEquality);
+
+        [collectionContext deleteInSectionController:self atIndexes:result.deletes];
+        [collectionContext insertInSectionController:self atIndexes:result.inserts];
+
+        for (IGListMoveIndex *move in result.moves) {
+            [collectionContext moveInSectionController:self fromIndex:move.from toIndex:move.to];
+        }
+
+        self.state = IGListAutoSectionStateUpdateApplied;
+    } completion:^(BOOL finished) {
+        self.state = IGListAutoSectionStateIdle;
+
+        // "reload" cells after updating since the cells can't be moved and reloaded at the same time.
+        // this lets the cell do an animated move and then update its contents
+        [result.updates enumerateIndexesUsingBlock:^(NSUInteger oldUpdatedIndex, BOOL *stop) {
+            id identifier = [oldViewModels[oldUpdatedIndex] diffIdentifier];
+            const NSInteger indexAfterUpdate = [result newIndexForIdentifier:identifier];
+            if (indexAfterUpdate != NSNotFound) {
+                UICollectionViewCell<IGListBindable> *cell = [collectionContext cellForItemAtIndex:indexAfterUpdate
+                                                                                 sectionController:self];
+                [cell bindViewModel:self.viewModels[indexAfterUpdate]];
+            }
+        }];
+    }];
+}
+
+#pragma mark - IGListSectionType
+
+- (NSInteger)numberOfItems {
+    return self.viewModels.count;
+}
+
+- (CGSize)sizeForItemAtIndex:(NSInteger)index {
+    return [self.dataSource sizeForViewModel:self.viewModels[index]];
+}
+
+- (UICollectionViewCell *)cellForItemAtIndex:(NSInteger)index {
+    id<IGListDiffable> viewModel = self.viewModels[index];
+    UICollectionViewCell<IGListBindable> *cell = [self.dataSource cellForViewModel:viewModel atIndex:index];
+    [cell bindViewModel:viewModel];
+    return cell;
+}
+
+- (void)didUpdateToObject:(id)object {
+    id oldObject = self.object;
+    self.object = object;
+
+    if (oldObject == nil) {
+        self.viewModels = [self.dataSource viewModelsForObject:object];
+    } else {
+        [self updateAnimated:YES completion:nil];
+    }
+//    self.viewModels = [self.dataSource viewModelsForObject:object];
+
+    // atm this will queue an update next turn which isn't ideal. really we want to unload this update right here and now
+    // maybe we can update performBatchAnimated:completion to fire if we're inside an update block?
+//    [self updateAnimated:YES completion:nil];
+}
+
+- (void)didSelectItemAtIndex:(NSInteger)index {
+    // would be nice to have a "selection delegate" here
+}
+
+@end

Source/IGListBindable.h

@@ -0,0 +1,18 @@
+/**
+ * Copyright (c) 2016-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#import <Foundation/Foundation.h>
+
+@protocol IGListDiffable;
+
+@protocol IGListBindable <NSObject>
+
+- (void)bindViewModel:(id)viewModel;
+
+@end

Source/IGListKit.h

@@ -28,6 +28,8 @@ FOUNDATION_EXPORT const unsigned char IGListKitVersionString[];
 #import <IGListKit/IGListAdapterDelegate.h>
 #import <IGListKit/IGListAdapterUpdater.h>
 #import <IGListKit/IGListAdapterUpdaterDelegate.h>
+#import <IGListKit/IGListAutoSectionController.h>
+#import <IGListKit/IGListBindable.h>
 #import <IGListKit/IGListCollectionContext.h>
 #import <IGListKit/IGListCollectionView.h>
 #import <IGListKit/IGListDisplayDelegate.h>

Source/Internal/IGListAdapterUpdaterInternal.h

@@ -13,6 +13,14 @@
 #import <IGListKit/IGListMoveIndexPath.h>
 
 #import "IGListAdapterUpdater.h"
+#import "IGListBatchUpdatesCollection.h"
+
+typedef NS_ENUM (NSInteger, IGListBatchUpdateState) {
+    IGListBatchUpdateStateIdle,
+    IGListBatchUpdateStateQueuedBatchUpdate,
+    IGListBatchUpdateStateExecutingBatchUpdateBlock,
+    IGListBatchUpdateStateExecutedBatchUpdateBlock,
+};
 
 NS_ASSUME_NONNULL_BEGIN
 
@@ -32,19 +40,21 @@ FOUNDATION_EXTERN void convertReloadToDeleteInsert(NSMutableIndexSet *reloads,
 
 @property (nonatomic, assign) BOOL queuedUpdateIsAnimated;
 
-@property (nonatomic, strong, readonly) NSMutableSet<NSIndexPath *> *deleteIndexPaths;
-@property (nonatomic, strong, readonly) NSMutableSet<NSIndexPath *> *insertIndexPaths;
-@property (nonatomic, strong, readonly) NSMutableSet<NSIndexPath *> *reloadIndexPaths;
-@property (nonatomic, strong, readonly) NSMutableSet<IGListMoveIndexPath *> *moveIndexPaths;
-@property (nonatomic, strong, readonly) NSMutableIndexSet *reloadSections;
+//@property (nonatomic, strong, readonly) NSMutableSet<NSIndexPath *> *deleteIndexPaths;
+//@property (nonatomic, strong, readonly) NSMutableSet<NSIndexPath *> *insertIndexPaths;
+//@property (nonatomic, strong, readonly) NSMutableSet<NSIndexPath *> *reloadIndexPaths;
+//@property (nonatomic, strong, readonly) NSMutableSet<IGListMoveIndexPath *> *moveIndexPaths;
+//@property (nonatomic, strong, readonly) NSMutableIndexSet *reloadSections;
+@property (nonatomic, strong) IGListBatchUpdatesCollection *updateCollection;
 
 @property (nonatomic, copy, nullable) IGListObjectTransitionBlock objectTransitionBlock;
 @property (nonatomic, copy, nullable) NSMutableArray<IGListItemUpdateBlock> *itemUpdateBlocks;
 
 @property (nonatomic, copy, nullable) IGListReloadUpdateBlock reloadUpdates;
 @property (nonatomic, assign, getter=hasQueuedReloadData) BOOL queuedReloadData;
 
-@property (nonatomic, assign) BOOL batchUpdateOrReloadInProgress;
+//@property (nonatomic, assign) BOOL batchUpdateOrReloadInProgress;
+@property (nonatomic, assign) IGListBatchUpdateState state;
 
 - (void)performReloadDataWithCollectionView:(UICollectionView *)collectionView;
 - (void)performBatchUpdatesWithCollectionView:(UICollectionView *)collectionView;

Source/Internal/IGListBatchUpdatesCollection.h

@@ -0,0 +1,28 @@
+//
+//  IGListBatchUpdatesCollection.h
+//  IGListKit
+//
+//  Created by Ryan Nystrom on 1/26/17.
+//  Copyright © 2017 Instagram. All rights reserved.
+//
+
+#import <Foundation/Foundation.h>
+
+@class IGListMoveIndex;
+@class IGListMoveIndexPath;
+
+@interface IGListBatchUpdatesCollection : NSObject
+
+//@property (nonatomic, strong, readonly) NSMutableIndexSet *sectionInserts;
+@property (nonatomic, strong, readonly) NSMutableIndexSet *sectionReloads;
+//@property (nonatomic, strong, readonly) NSMutableIndexSet *sectionDeletes;
+//@property (nonatomic, strong, readonly) NSMutableSet<IGListMoveIndex *> *sectionMoves;
+@property (nonatomic, strong, readonly) NSMutableSet<NSIndexPath *> *itemInserts;
+@property (nonatomic, strong, readonly) NSMutableSet<NSIndexPath *> *itemDeletes;
+@property (nonatomic, strong, readonly) NSMutableSet<NSIndexPath *> *itemReloads;
+@property (nonatomic, strong, readonly) NSMutableSet<IGListMoveIndexPath *> *itemMoves;
+@property (nonatomic, strong, readonly) NSMutableArray<void (^)(BOOL)> *completionBlocks;
+
+//- (BOOL)hasChanges;
+
+@end

Source/Internal/IGListBatchUpdatesCollection.m

@@ -0,0 +1,34 @@
+//
+//  IGListBatchUpdatesCollection.m
+//  IGListKit
+//
+//  Created by Ryan Nystrom on 1/26/17.
+//  Copyright © 2017 Instagram. All rights reserved.
+//
+
+#import "IGListBatchUpdatesCollection.h"
+
+@implementation IGListBatchUpdatesCollection
+
+- (instancetype)init {
+    if (self = [super init]) {
+        _sectionReloads = [NSMutableIndexSet new];
+        _itemInserts = [NSMutableSet new];
+        _itemMoves = [NSMutableSet new];
+        _itemReloads = [NSMutableSet new];
+        _itemDeletes = [NSMutableSet new];
+        _completionBlocks = [NSMutableArray new];
+    }
+    return self;
+}
+
+//- (BOOL)hasChanges {
+//    return self.sectionReloads.count > 0
+//    || self.itemInserts.count > 0
+//    || self.itemMoves.count > 0
+//    || self.itemReloads.count > 0
+//    || self.itemDeletes.count > 0
+//    || self.completionBlocks.count > 0;
+//}
+
+@end

Tests/IGListAdapterUpdaterTests.m

@@ -505,4 +505,75 @@ - (void)test_whenCollectionViewNotInWindow_andBackgroundReloadFlag_isDefaultYES_
     [mockDelegate verify];
 }
 
+- (void)test_ {
+    IGSectionObject *object = [IGSectionObject sectionWithObjects:@[@0, @1, @2]];
+    self.dataSource.sections = @[object];
+
+    __block BOOL reloadDataCompletionExecuted = NO;
+    [self.updater reloadDataWithCollectionView:self.collectionView reloadUpdateBlock:^{} completion:^(BOOL finished) {
+        reloadDataCompletionExecuted = YES;
+    }];
+
+    XCTestExpectation *expectation = genExpectation;
+    [self.updater performUpdateWithCollectionView:self.collectionView animated:YES itemUpdates:^{
+        object.objects = @[@2, @1, @4, @5];
+        [self.updater insertItemsIntoCollectionView:self.collectionView indexPaths:@[
+                                                                                     [NSIndexPath indexPathForItem:2 inSection:0],
+                                                                                     [NSIndexPath indexPathForItem:3 inSection:0],
+                                                                                     ]];
+        [self.updater deleteItemsFromCollectionView:self.collectionView indexPaths:@[
+                                                                                     [NSIndexPath indexPathForItem:0 inSection:0],
+                                                                                     ]];
+        [self.updater moveItemInCollectionView:self.collectionView
+                                 fromIndexPath:[NSIndexPath indexPathForItem:2 inSection:0]
+                                   toIndexPath:[NSIndexPath indexPathForItem:0 inSection:0]];
+    } completion:^(BOOL finished) {
+        XCTAssertTrue(reloadDataCompletionExecuted);
+        [expectation fulfill];
+    }];
+
+    [self waitForExpectationsWithTimeout:15 handler:nil];
+}
+
+- (void)test_2 {
+    [self.collectionView removeFromSuperview];
+
+    IGSectionObject *object = [IGSectionObject sectionWithObjects:@[@0, @1, @2]];
+    self.dataSource.sections = @[object];
+
+    __block BOOL objectTransitionBlockExecuted = NO;
+    __block BOOL completionBlockExecuted = NO;
+    [self.updater performUpdateWithCollectionView:self.collectionView
+                                      fromObjects:self.dataSource.sections
+                                        toObjects:self.dataSource.sections
+                                         animated:YES
+                            objectTransitionBlock:^(NSArray *toObjects) {
+                                objectTransitionBlockExecuted = YES;
+                            }
+                                       completion:^(BOOL finished) {
+                                           completionBlockExecuted = YES;
+                                       }];
+
+    XCTestExpectation *expectation = genExpectation;
+    [self.updater performUpdateWithCollectionView:self.collectionView animated:YES itemUpdates:^{
+        object.objects = @[@2, @1, @4, @5];
+        [self.updater insertItemsIntoCollectionView:self.collectionView indexPaths:@[
+                                                                                     [NSIndexPath indexPathForItem:2 inSection:0],
+                                                                                     [NSIndexPath indexPathForItem:3 inSection:0],
+                                                                                     ]];
+        [self.updater deleteItemsFromCollectionView:self.collectionView indexPaths:@[
+                                                                                     [NSIndexPath indexPathForItem:0 inSection:0],
+                                                                                     ]];
+        [self.updater moveItemInCollectionView:self.collectionView
+                                 fromIndexPath:[NSIndexPath indexPathForItem:2 inSection:0]
+                                   toIndexPath:[NSIndexPath indexPathForItem:0 inSection:0]];
+    } completion:^(BOOL finished) {
+        XCTAssertTrue(objectTransitionBlockExecuted);
+        XCTAssertTrue(completionBlockExecuted);
+        [expectation fulfill];
+    }];
+
+    [self waitForExpectationsWithTimeout:15 handler:nil];
+}
+
 @end