created IGListCollectionView

Summary: * IGListCollectionView passes update information to IGListCollectionViewLayout.

Reviewed By: rnystrom

Differential Revision: D6510139

fbshipit-source-id: ada194d009eca7f308887ec592ecc41fb9557855

Source/IGListCollectionView.h

@@ -0,0 +1,44 @@
+/**
+ * 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>
+
+@class IGListCollectionViewLayout;
+
+NS_ASSUME_NONNULL_BEGIN
+
+/**
+ This `UICollectionView` subclass allows for partial layout invalidation using `IGListCollectionViewLayout`.
+
+ @note When updating a collection view (ex: calling `-insertSections`), `-invalidateLayoutWithContext` gets called on
+ the layout object. However, the invalidation context doesn't provide details on which index paths are being modified,
+ which typically forces a full layout re-calculation. `IGListCollectionView` gives `IGListCollectionViewLayout` the
+ missing information to re-calculate only the modified layout attributes.
+ */
+NS_SWIFT_NAME(ListCollectionView)
+@interface IGListCollectionView : UICollectionView
+
+/**
+ Create a new view with an `IGListcollectionViewLayout` class or subclass.
+
+ @param frame The frame to initialize with.
+ @param collectionViewLayout The layout to use with the collection view.
+
+ @note You can initialize a new view with a base layout by simply calling `-[IGListCollectionView initWithFrame:]`.
+ */
+- (instancetype)initWithFrame:(CGRect)frame listCollectionViewLayout:(IGListCollectionViewLayout *)collectionViewLayout NS_DESIGNATED_INITIALIZER;
+
+/**
+ :nodoc:
+ */
+- (instancetype)initWithFrame:(CGRect)frame collectionViewLayout:(UICollectionViewLayout *)collectionViewLayout NS_UNAVAILABLE;
+
+@end
+
+NS_ASSUME_NONNULL_END

Source/IGListCollectionView.m

@@ -0,0 +1,106 @@
+/**
+ * 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 "IGListCollectionView.h"
+
+#import "IGListCollectionViewLayout.h"
+
+@implementation IGListCollectionView
+
+#pragma mark - Init
+
+- (instancetype)initWithFrame:(CGRect)frame {
+    IGListCollectionViewLayout *layout = [[IGListCollectionViewLayout alloc] initWithStickyHeaders:NO topContentInset:0 stretchToEdge:YES];
+    return [self initWithFrame:frame listCollectionViewLayout:layout];
+}
+
+- (instancetype)initWithFrame:(CGRect)frame listCollectionViewLayout:(IGListCollectionViewLayout *)collectionViewLayout {
+    return [super initWithFrame:frame collectionViewLayout:collectionViewLayout];
+}
+
+#pragma mark - IGListCollectionViewLayout
+
+- (IGListCollectionViewLayout *)listLayout {
+    if ([self.collectionViewLayout isKindOfClass:[IGListCollectionViewLayout class]]) {
+        return (IGListCollectionViewLayout *)self.collectionViewLayout;
+    }
+
+    return nil;
+}
+
+#pragma mark - Overides reloads
+
+- (void)reloadItemsAtIndexPaths:(NSArray<NSIndexPath *> *)indexPaths {
+    [self didModifyIndexPaths:indexPaths];
+    [super reloadItemsAtIndexPaths:indexPaths];
+}
+
+- (void)reloadSections:(NSIndexSet *)sections {
+    [self didModifySections:sections];
+    [super reloadSections:sections];
+}
+
+#pragma mark - Override deletes
+
+- (void)deleteItemsAtIndexPaths:(NSArray<NSIndexPath *> *)indexPaths {
+    [self didModifyIndexPaths:indexPaths];
+    [super deleteItemsAtIndexPaths:indexPaths];
+}
+
+- (void)deleteSections:(NSIndexSet *)sections {
+    [self didModifySections:sections];
+    [super deleteSections:sections];
+}
+
+#pragma mark - Override inserts
+
+- (void)insertItemsAtIndexPaths:(NSArray<NSIndexPath *> *)indexPaths {
+    [self didModifyIndexPaths:indexPaths];
+    [super insertItemsAtIndexPaths:indexPaths];
+}
+
+- (void)insertSections:(NSIndexSet *)sections {
+    [self didModifySections:sections];
+    [super insertSections:sections];
+}
+
+#pragma mark - Override moves
+
+- (void)moveItemAtIndexPath:(NSIndexPath *)indexPath toIndexPath:(NSIndexPath *)newIndexPath {
+    [self didModifyIndexPaths:@[indexPath, newIndexPath]];
+    [super moveItemAtIndexPath:indexPath toIndexPath:newIndexPath];
+}
+
+- (void)moveSection:(NSInteger)section toSection:(NSInteger)newSection {
+    [self didModifySection:MIN(section, newSection)];
+    [super moveSection:section toSection:newSection];
+}
+
+#pragma mark - Modify section
+
+- (void)didModifySections:(NSIndexSet *)sections {
+    if (sections.count == 0) {
+        return;
+    }
+    [self didModifySection:sections.firstIndex];
+}
+
+- (void)didModifySection:(NSUInteger)section {
+    [self.listLayout didModifySection:section];
+}
+
+#pragma mark - Modified index path
+
+- (void)didModifyIndexPaths:(NSArray<NSIndexPath *> *)indexPaths {
+    for (NSIndexPath *indexPath in indexPaths) {
+        [self didModifySection:indexPath.section];
+    }
+}
+
+@end

Tests/IGListCollectionViewTests.m

@@ -0,0 +1,189 @@
+/**
+ * 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 <XCTest/XCTest.h>
+
+#import <IGListKit/IGListCollectionView.h>
+
+#import "IGLayoutTestItem.h"
+#import "IGLayoutTestSection.h"
+#import "IGLayoutTestDataSource.h"
+#import "IGListTestHelpers.h"
+
+@interface IGListCollectionViewTests : XCTestCase
+
+@property (nonatomic, strong) IGListCollectionView *collectionView;
+@property (nonatomic, strong) IGLayoutTestDataSource *dataSource;
+
+@end
+
+@implementation IGListCollectionViewTests
+
+- (void)setUp {
+    [super setUp];
+    self.dataSource = [IGLayoutTestDataSource new];
+    self.collectionView = [[IGListCollectionView alloc] initWithFrame:CGRectMake(0, 0, 100, 100)];
+    self.collectionView.dataSource = self.dataSource;
+    self.collectionView.delegate = self.dataSource;
+    [self.dataSource configCollectionView:self.collectionView];
+}
+
+#pragma mark - Reload All
+
+- (void)test_whenReloadData_thatEntireLayoutUpdates {
+    self.dataSource.sections = @[
+                                 genLayoutTestSection(@[genLayoutTestItem(CGSizeMake(10, 10))])
+                                 ];
+    [self.collectionView reloadData];
+    [self.collectionView layoutIfNeeded];
+
+    self.dataSource.sections = @[
+                                 genLayoutTestSection(@[genLayoutTestItem(CGSizeMake(20, 20))]),
+                                 genLayoutTestSection(@[genLayoutTestItem(CGSizeMake(10, 10))])
+                                 ];
+    [self.collectionView reloadData];
+    [self.collectionView layoutIfNeeded];
+
+    IGAssertEqualFrame([self cellForSection:0 item:0].frame, 0, 0, 20, 20);
+    IGAssertEqualFrame([self cellForSection:1 item:0].frame, 20, 0, 10, 10);
+}
+
+#pragma mark - Insert/Delete/Reload/Move
+
+- (void)test_whenInsertingSection_thatLayoutPartiallyUpdates {
+    self.dataSource.sections = @[
+                                 genLayoutTestSection(@[genLayoutTestItem(CGSizeMake(10, 10))])
+                                 ];
+    [self.collectionView reloadData];
+    [self.collectionView layoutIfNeeded];
+
+    self.dataSource.sections = @[
+                                 genLayoutTestSection(@[genLayoutTestItem(CGSizeMake(20, 20))]),
+                                 genLayoutTestSection(@[genLayoutTestItem(CGSizeMake(10, 10))])
+                                 ];
+    [self.collectionView insertSections:[NSIndexSet indexSetWithIndex:1]];
+
+    // check that section 0 wasn't updated
+    IGAssertEqualFrame([self cellForSection:0 item:0].frame, 0, 0, 10, 10);
+    // check that section 1 was updated
+    IGAssertEqualFrame([self cellForSection:1 item:0].frame, 10, 0, 10, 10);
+}
+
+- (void)test_whenDeletingSection_thatLayoutPartiallyUpdates {
+    self.dataSource.sections = @[
+                                 genLayoutTestSection(@[genLayoutTestItem(CGSizeMake(10, 10))]),
+                                 genLayoutTestSection(@[genLayoutTestItem(CGSizeMake(10, 10))])
+                                 ];
+    [self.collectionView reloadData];
+    [self.collectionView layoutIfNeeded];
+
+    self.dataSource.sections = @[
+                                 genLayoutTestSection(@[genLayoutTestItem(CGSizeMake(20, 20))]),
+                                 ];
+    [self.collectionView deleteSections:[NSIndexSet indexSetWithIndex:1]];
+
+    // check that section 0 wasn't updated
+    IGAssertEqualFrame([self cellForSection:0 item:0].frame, 0, 0, 10, 10);
+}
+
+- (void)test_whenReloadingSection_thatLayoutPartiallyUpdates {
+    self.dataSource.sections = @[
+                                 genLayoutTestSection(@[genLayoutTestItem(CGSizeMake(10, 10))]),
+                                 genLayoutTestSection(@[genLayoutTestItem(CGSizeMake(10, 10))])
+                                 ];
+    [self.collectionView reloadData];
+    [self.collectionView layoutIfNeeded];
+
+    self.dataSource.sections = @[
+                                 genLayoutTestSection(@[genLayoutTestItem(CGSizeMake(20, 20))]),
+                                 genLayoutTestSection(@[genLayoutTestItem(CGSizeMake(20, 20))]),
+                                 ];
+    [self.collectionView reloadSections:[NSIndexSet indexSetWithIndex:1]];
+
+    // check that section 0 wasn't updated
+    IGAssertEqualFrame([self cellForSection:0 item:0].frame, 0, 0, 10, 10);
+    // check that section 1 was updated
+    IGAssertEqualFrame([self cellForSection:1 item:0].frame, 10, 0, 20, 20);
+}
+
+- (void)test_whenMoveSection_thatLayoutPartiallyUpdates {
+    self.dataSource.sections = @[
+                                 genLayoutTestSection(@[genLayoutTestItem(CGSizeMake(10, 10))]),
+                                 genLayoutTestSection(@[genLayoutTestItem(CGSizeMake(20, 20))]),
+                                 genLayoutTestSection(@[genLayoutTestItem(CGSizeMake(30, 30))])
+                                 ];
+    [self.collectionView reloadData];
+    [self.collectionView layoutIfNeeded];
+
+    self.dataSource.sections = @[
+                                 genLayoutTestSection(@[genLayoutTestItem(CGSizeMake(40, 40))]),
+                                 genLayoutTestSection(@[genLayoutTestItem(CGSizeMake(30, 30))]),
+                                 genLayoutTestSection(@[genLayoutTestItem(CGSizeMake(20, 20))]),
+                                 ];
+    [self.collectionView moveSection:1 toSection:2];
+
+    // check that section 0 wasn't updated
+    IGAssertEqualFrame([self cellForSection:0 item:0].frame, 0, 0, 10, 10);
+    // check that section 1 was updated
+    IGAssertEqualFrame([self cellForSection:1 item:0].frame, 10, 0, 30, 30);
+    // check that section 2 was updated
+    IGAssertEqualFrame([self cellForSection:2 item:0].frame, 40, 0, 20, 20);
+}
+
+#pragma mark - Batch
+
+- (void)test_whenInsertDeleteMoveSection_thatLayoutPartiallyUpdates {
+    self.dataSource.sections = @[
+                                 genLayoutTestSection(@[genLayoutTestItem(CGSizeMake(1, 1))]),
+                                 genLayoutTestSection(@[genLayoutTestItem(CGSizeMake(2, 2))]),
+                                 genLayoutTestSection(@[genLayoutTestItem(CGSizeMake(3, 3))]),
+                                 genLayoutTestSection(@[genLayoutTestItem(CGSizeMake(4, 4))]),
+                                 ];
+    [self.collectionView reloadData];
+    [self.collectionView layoutIfNeeded];
+
+    self.dataSource.sections = @[
+                                 genLayoutTestSection(@[genLayoutTestItem(CGSizeMake(0, 0))]),
+                                 genLayoutTestSection(@[genLayoutTestItem(CGSizeMake(4, 4))]),
+                                 genLayoutTestSection(@[genLayoutTestItem(CGSizeMake(3, 3))]),
+                                 genLayoutTestSection(@[genLayoutTestItem(CGSizeMake(5, 5))]),
+                                 ];
+
+    XCTestExpectation *expectation = [self expectationWithDescription:NSStringFromSelector(_cmd)];
+
+    [self.collectionView performBatchUpdates:^{
+        [self.collectionView deleteSections:[NSIndexSet indexSetWithIndex:1]]; // deleted (2, 2)
+        [self.collectionView moveSection:3 toSection:1]; // move (4, 4)
+        [self.collectionView insertSections:[NSIndexSet indexSetWithIndex:3]]; // inserted (5, 5)
+    } completion:^(BOOL finished) {
+        [self.collectionView layoutIfNeeded];
+        [expectation fulfill];
+
+        // check that section 0 wasn't updated
+        IGAssertEqualFrame([self cellForSection:0 item:0].frame, 0, 0, 1, 1);
+        // check that section 1 was updated
+        IGAssertEqualFrame([self cellForSection:1 item:0].frame, 1, 0, 4, 4);
+        // check that section 2 was updated
+        IGAssertEqualFrame([self cellForSection:2 item:0].frame, 5, 0, 3, 3);
+        // check that section 3 was updated
+        IGAssertEqualFrame([self cellForSection:3 item:0].frame, 8, 0, 5, 5);
+    }];
+
+    [self waitForExpectationsWithTimeout:30 handler:^(NSError * _Nullable error) {
+        XCTAssertNil(error);
+    }];
+}
+
+#pragma mark - Helpers
+
+- (UICollectionViewCell *)cellForSection:(NSInteger)section item:(NSInteger)item {
+    return [self.collectionView cellForItemAtIndexPath:genIndexPath(section, item)];
+}
+
+@end

Tests/Objects/IGLayoutTestItem.h

@@ -9,6 +9,8 @@
 
 #import <UIKit/UIKit.h>
 
+#define genLayoutTestItem(s) [[IGLayoutTestItem alloc] initWithSize:s]
+
 @interface IGLayoutTestItem : NSObject
 
 @property (nonatomic, assign, readonly) CGSize size;

Tests/Objects/IGLayoutTestSection.h

@@ -11,6 +11,8 @@
 
 @class IGLayoutTestItem;
 
+#define genLayoutTestSection(i) [[IGLayoutTestSection alloc] initWithItems:i]
+
 @interface IGLayoutTestSection : NSObject
 
 @property (nonatomic, assign, readonly) UIEdgeInsets insets;
@@ -20,11 +22,13 @@
 @property (nonatomic, assign, readonly) CGFloat footerHeight;
 @property (nonatomic, strong, readonly) NSArray<IGLayoutTestItem *> *items;
 
+- (instancetype)initWithItems:(NSArray<IGLayoutTestItem *> *)items;
+
 - (instancetype)initWithInsets:(UIEdgeInsets)insets
                    lineSpacing:(CGFloat)lineSpacing
               interitemSpacing:(CGFloat)interitemSpacing
                   headerHeight:(CGFloat)headerHeight
                   footerHeight:(CGFloat)footerHeight
-                         items:(NSArray<IGLayoutTestItem *> *)items;
+                         items:(NSArray<IGLayoutTestItem *> *)items NS_DESIGNATED_INITIALIZER;
 
 @end

Tests/Objects/IGLayoutTestSection.m

@@ -11,6 +11,15 @@
 
 @implementation IGLayoutTestSection
 
+- (instancetype)initWithItems:(NSArray<IGLayoutTestItem *> *)items {
+    return [self initWithInsets:UIEdgeInsetsZero
+                    lineSpacing:0
+               interitemSpacing:0
+                   headerHeight:0
+                   footerHeight:0
+                          items:items];
+}
+
 - (instancetype)initWithInsets:(UIEdgeInsets)insets
                    lineSpacing:(CGFloat)lineSpacing
               interitemSpacing:(CGFloat)interitemSpacing