Specify end position for -scrollToObject

Summary: Closes https://github.com/Instagram/IGListKit/pull/196 Differential Revision: D4203333 Pulled By: rnystrom fbshipit-source-id: 6ef0544c8e4f77afa25dd56df90c726d287c66a4
2026-05-22 16:58:23 +00:00 · 2016-11-18 10:50:24 -08:00 · 2016-11-18 10:50:24 -08:00 · 14e0727eff
commit 14e0727eff
parent 74affe0887
4 changed files with 78 additions and 28 deletions
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@ -11,9 +11,9 @@ This release closes the [2.0.0 milestone](https://github.com/Instagram/IGListKit

 - Diff result method `-resultWithUpdatedMovesAsDeleteInserts` removed and replaced with `-resultForBatchUpdates` [(b5aa5e3)](https://github.com/Instagram/IGListKit/commit/b5aa5e39002854c947e777c11ae241f67f24d19c)
 - `IGListDiffable` equality method changed from `isEqual:` to `isEqualToDiffableObject:` [(ab890fc)](https://github.com/Instagram/IGListKit/commit/ab890fc6070f170a2db5a383a6296e62dcf75678)
+- Scrolling method changed from `-scrollToObject:supplementaryKinds:scrollDirection:animated` to `-scrollToObject:supplementaryKinds:scrollDirection:atScrollPosition:animated`. Added support for specifying end position. [Bofei Zhu](https://github.com/zhubofei) [(#196)](https://github.com/Instagram/IGListKit/pull/196)
 - Change `NSUInteger` to `NSInteger` in public API [Suraya Shivji](https://github.com/surayashivji) [(#200)](https://github.com/Instagram/IGListKit/issues/200)

-
 ### Enhancements

 - Added support for supplementaryViews created from nibs. [Rawlinxx](https://github.com/rawlinxx) [(#90)](https://github.com/Instagram/IGListKit/pull/90)
@ -21,7 +21,7 @@ This release closes the [2.0.0 milestone](https://github.com/Instagram/IGListKit
 - Added an additional initializer for `IGListSingleSectionController` to be able to support single sections created from nibs. An example can be found [here](Examples/Examples-iOS/IGListKitExamples/ViewControllers/SingleSectionViewController.swift).
 - Fixed `-[IGListAdapter reloadDataWithCompletion:]` not returning early when `collectionView` or `dataSource` is nil and `completion` is nil. [Ben Asher](https://github.com/benasher44) [(#51)](https://github.com/Instagram/IGListKit/pull/51)
 - Added `-isFirstSection` and `-isLastSection` APIs to `IGListSectionController`
- Added support for cells created from storyboard. [Bofei Zhu](https://github.com/zhubofei) [(#92)](https://github.com/Instagram/IGListKit/pull/92)
+- Added support for cells and supplementaryViews created from storyboard. [Bofei Zhu](https://github.com/zhubofei) [(#92)](https://github.com/Instagram/IGListKit/pull/92)
 - Added examples for Today & iMessage extensions. [Sherlouk](https://github.com/Sherlouk) [(#112)](https://github.com/Instagram/IGListKit/pull/112)
 - Added `tvOS` support. [Jesse Squires](https://github.com/jessesquires) [(#137)](https://github.com/Instagram/IGListKit/pull/137)
 - Added `tvOS` example pack. [Sherlouk](https://github.com/Sherlouk) [(#141)](https://github.com/Instagram/IGListKit/pull/141)
--- a/Source/IGListAdapter.h
+++ b/Source/IGListAdapter.h
@ -195,11 +195,13 @@ IGLK_SUBCLASSING_RESTRICTED
 @param object             The object to which to scroll.
 @param supplementaryKinds The types of supplementary views in the section.
 @param scrollDirection    A flag indicating the direction to scroll.
+ @param scrollPosition     An option that specifies where the item should be positioned when scrolling finishes. 
 @param animated           A flag indicating if the transition should be animated.
 */
 - (void)scrollToObject:(id)object
    supplementaryKinds:(nullable NSArray<NSString *> *)supplementaryKinds
       scrollDirection:(UICollectionViewScrollDirection)scrollDirection
+        scrollPosition:(UICollectionViewScrollPosition)scrollPosition
              animated:(BOOL)animated;

 /**
--- a/Source/IGListAdapter.m
+++ b/Source/IGListAdapter.m
@ -141,6 +141,7 @@
 - (void)scrollToObject:(id)object
    supplementaryKinds:(NSArray<NSString *> *)supplementaryKinds
       scrollDirection:(UICollectionViewScrollDirection)scrollDirection
+        scrollPosition:(UICollectionViewScrollPosition)scrollPosition
              animated:(BOOL)animated {
    IGAssertMainThread();
    IGParameterAssert(object != nil);
@ -166,33 +167,72 @@
    NSIndexPath *indexPath = [NSIndexPath indexPathForItem:0 inSection:section];
    NSArray *attributes = [self layoutAttributesForIndexPath:indexPath supplementaryKinds:supplementaryKinds];

-    CGFloat offset = 0.0;
+    CGFloat offsetMin = 0.0;
+    CGFloat offsetMax = 0.0;
    for (UICollectionViewLayoutAttributes *attribute in attributes) {
        const CGRect frame = attribute.frame;
-        CGFloat origin;
+        CGFloat originMin;
+        CGFloat endMax;
        switch (scrollDirection) {
            case UICollectionViewScrollDirectionHorizontal:
-                origin = CGRectGetMinX(frame);
+                originMin = CGRectGetMinX(frame);
+                endMax = CGRectGetMaxX(frame);
                break;
            case UICollectionViewScrollDirectionVertical:
-                origin = CGRectGetMinY(frame);
+                originMin = CGRectGetMinY(frame);
+                endMax = CGRectGetMaxY(frame);
                break;
        }

        // find the minimum origin value of all the layout attributes
-        if (attribute == attributes.firstObject || origin < offset) {
-            offset = origin;
+        if (attribute == attributes.firstObject || originMin < offsetMin) {
+            offsetMin = originMin;
+        }
+        // find the maximum end value of all the layout attributes
+        if (attribute == attributes.firstObject || endMax > offsetMax) {
+            offsetMax = endMax;
        }
    }
-
+    
+    const CGFloat offsetMid = (offsetMin + offsetMax) / 2.0;
+    const CGFloat collectionViewWidth = collectionView.bounds.size.width;
+    const CGFloat collectionViewHeight = collectionView.bounds.size.height;
    const UIEdgeInsets contentInset = collectionView.contentInset;
    CGPoint contentOffset = collectionView.contentOffset;
    switch (scrollDirection) {
        case UICollectionViewScrollDirectionHorizontal:
-            contentOffset.x = offset - contentInset.left;
+            switch (scrollPosition) {
+                case UICollectionViewScrollPositionRight:
+                    contentOffset.x = offsetMax - collectionViewWidth - contentInset.left;
+                    break;
+                case UICollectionViewScrollPositionCenteredHorizontally:
+                    contentOffset.x = offsetMid - collectionViewWidth / 2.0 - contentInset.left;
+                    break;
+                case UICollectionViewScrollPositionLeft:
+                case UICollectionViewScrollPositionNone:
+                case UICollectionViewScrollPositionTop:
+                case UICollectionViewScrollPositionBottom:
+                case UICollectionViewScrollPositionCenteredVertically:
+                    contentOffset.x = offsetMin - contentInset.left;
+                    break;
+            }
            break;
        case UICollectionViewScrollDirectionVertical:
-            contentOffset.y = offset - contentInset.top;
+            switch (scrollPosition) {
+                case UICollectionViewScrollPositionBottom:
+                    contentOffset.y = offsetMax - collectionViewHeight - contentInset.top;
+                    break;
+                case UICollectionViewScrollPositionCenteredVertically:
+                    contentOffset.y = offsetMid - collectionViewHeight / 2.0 - contentInset.top;
+                    break;
+                case UICollectionViewScrollPositionTop:
+                case UICollectionViewScrollPositionNone:
+                case UICollectionViewScrollPositionLeft:
+                case UICollectionViewScrollPositionRight:
+                case UICollectionViewScrollPositionCenteredHorizontally:
+                    contentOffset.y = offsetMin - contentInset.top;
+                    break;
+            }
            break;
    }

--- a/Tests/IGListAdapterTests.m
+++ b/Tests/IGListAdapterTests.m
@ -546,14 +546,18 @@ XCTAssertEqual(CGPointEqualToPoint(point, p), YES); \
    self.dataSource.objects = @[@1, @2, @3, @4, @5, @6];
    [self.adapter reloadDataWithCompletion:nil];
    XCTAssertEqual([self.collectionView numberOfSections], 6);
-    [self.adapter scrollToObject:@1 supplementaryKinds:nil scrollDirection:UICollectionViewScrollDirectionVertical animated:NO];
+    [self.adapter scrollToObject:@1 supplementaryKinds:nil scrollDirection:UICollectionViewScrollDirectionVertical scrollPosition:UICollectionViewScrollPositionNone animated:NO];
    IGAssertEqualPoint([self.collectionView contentOffset], 0, 0);
-    [self.adapter scrollToObject:@2 supplementaryKinds:nil scrollDirection:UICollectionViewScrollDirectionVertical animated:NO];
+    [self.adapter scrollToObject:@2 supplementaryKinds:nil scrollDirection:UICollectionViewScrollDirectionVertical scrollPosition:UICollectionViewScrollPositionNone animated:NO];
    IGAssertEqualPoint([self.collectionView contentOffset], 0, 10);
-    [self.adapter scrollToObject:@3 supplementaryKinds:nil scrollDirection:UICollectionViewScrollDirectionVertical animated:NO];
+    [self.adapter scrollToObject:@3 supplementaryKinds:nil scrollDirection:UICollectionViewScrollDirectionVertical scrollPosition:UICollectionViewScrollPositionNone animated:NO];
    IGAssertEqualPoint([self.collectionView contentOffset], 0, 30);
-    [self.adapter scrollToObject:@6 supplementaryKinds:nil scrollDirection:UICollectionViewScrollDirectionVertical animated:NO];
+    [self.adapter scrollToObject:@6 supplementaryKinds:nil scrollDirection:UICollectionViewScrollDirectionVertical scrollPosition:UICollectionViewScrollPositionNone animated:NO];
    IGAssertEqualPoint([self.collectionView contentOffset], 0, 150);
+    [self.adapter scrollToObject:@6 supplementaryKinds:nil scrollDirection:UICollectionViewScrollDirectionVertical scrollPosition:UICollectionViewScrollPositionCenteredVertically animated:NO];
+    IGAssertEqualPoint([self.collectionView contentOffset], 0, 105);
+    [self.adapter scrollToObject:@6 supplementaryKinds:nil scrollDirection:UICollectionViewScrollDirectionVertical scrollPosition:UICollectionViewScrollPositionBottom animated:NO];
+    IGAssertEqualPoint([self.collectionView contentOffset], 0, 60);
 }

 - (void)test_whenScrollHorizontallyToItem {
@ -562,13 +566,17 @@ XCTAssertEqual(CGPointEqualToPoint(point, p), YES); \
    self.layout.scrollDirection = UICollectionViewScrollDirectionHorizontal;
    [self.adapter reloadDataWithCompletion:nil];
    XCTAssertEqual([self.collectionView numberOfSections], 6);
-    [self.adapter scrollToObject:@1 supplementaryKinds:nil scrollDirection:UICollectionViewScrollDirectionHorizontal animated:NO];
+    [self.adapter scrollToObject:@1 supplementaryKinds:nil scrollDirection:UICollectionViewScrollDirectionHorizontal scrollPosition:UICollectionViewScrollPositionNone animated:NO];
    IGAssertEqualPoint([self.collectionView contentOffset], 0, 0);
-    [self.adapter scrollToObject:@2 supplementaryKinds:nil scrollDirection:UICollectionViewScrollDirectionHorizontal animated:NO];
+    [self.adapter scrollToObject:@2 supplementaryKinds:nil scrollDirection:UICollectionViewScrollDirectionHorizontal scrollPosition:UICollectionViewScrollPositionNone animated:NO];
    IGAssertEqualPoint([self.collectionView contentOffset], 100, 0);
-    [self.adapter scrollToObject:@3 supplementaryKinds:nil scrollDirection:UICollectionViewScrollDirectionHorizontal animated:NO];
+    [self.adapter scrollToObject:@3 supplementaryKinds:nil scrollDirection:UICollectionViewScrollDirectionHorizontal scrollPosition:UICollectionViewScrollPositionNone animated:NO];
    IGAssertEqualPoint([self.collectionView contentOffset], 200, 0);
-    [self.adapter scrollToObject:@6 supplementaryKinds:nil scrollDirection:UICollectionViewScrollDirectionHorizontal animated:NO];
+    [self.adapter scrollToObject:@6 supplementaryKinds:nil scrollDirection:UICollectionViewScrollDirectionHorizontal scrollPosition:UICollectionViewScrollPositionNone animated:NO];
+    IGAssertEqualPoint([self.collectionView contentOffset], 500, 0);
+    [self.adapter scrollToObject:@6 supplementaryKinds:nil scrollDirection:UICollectionViewScrollDirectionHorizontal scrollPosition:UICollectionViewScrollPositionCenteredHorizontally animated:NO];
+    IGAssertEqualPoint([self.collectionView contentOffset], 500, 0);
+    [self.adapter scrollToObject:@6 supplementaryKinds:nil scrollDirection:UICollectionViewScrollDirectionHorizontal scrollPosition:UICollectionViewScrollPositionRight animated:NO];
    IGAssertEqualPoint([self.collectionView contentOffset], 500, 0);
    self.layout.scrollDirection = UICollectionViewScrollDirectionVertical;
 }
@ -588,9 +596,9 @@ XCTAssertEqual(CGPointEqualToPoint(point, p), YES); \
    [self.adapter performUpdatesAnimated:NO completion:nil];
    
    XCTAssertNotNil([self.collectionView supplementaryViewForElementKind:UICollectionElementKindSectionHeader atIndexPath:[NSIndexPath indexPathForItem:0 inSection:0]]);
-    [self.adapter scrollToObject:@1 supplementaryKinds:@[UICollectionElementKindSectionHeader] scrollDirection:UICollectionViewScrollDirectionVertical animated:NO];
+    [self.adapter scrollToObject:@1 supplementaryKinds:@[UICollectionElementKindSectionHeader] scrollDirection:UICollectionViewScrollDirectionVertical scrollPosition:UICollectionViewScrollPositionNone animated:NO];
    IGAssertEqualPoint([self.collectionView contentOffset], 0, 0);
-    [self.adapter scrollToObject:@2 supplementaryKinds:@[UICollectionElementKindSectionHeader] scrollDirection:UICollectionViewScrollDirectionVertical animated:NO];
+    [self.adapter scrollToObject:@2 supplementaryKinds:@[UICollectionElementKindSectionHeader] scrollDirection:UICollectionViewScrollDirectionVertical scrollPosition:UICollectionViewScrollPositionNone animated:NO];
    IGAssertEqualPoint([self.collectionView contentOffset], 0, 20);
 }

@ -610,9 +618,9 @@ XCTAssertEqual(CGPointEqualToPoint(point, p), YES); \
    
    XCTAssertNotNil([self.collectionView supplementaryViewForElementKind:UICollectionElementKindSectionHeader atIndexPath:[NSIndexPath indexPathForItem:0 inSection:0]]);
    XCTAssertNotNil([self.collectionView supplementaryViewForElementKind:UICollectionElementKindSectionFooter atIndexPath:[NSIndexPath indexPathForItem:0 inSection:0]]);
-    [self.adapter scrollToObject:@1 supplementaryKinds:@[UICollectionElementKindSectionHeader, UICollectionElementKindSectionFooter] scrollDirection:UICollectionViewScrollDirectionVertical animated:NO];
+    [self.adapter scrollToObject:@1 supplementaryKinds:@[UICollectionElementKindSectionHeader, UICollectionElementKindSectionFooter] scrollDirection:UICollectionViewScrollDirectionVertical scrollPosition:UICollectionViewScrollPositionNone animated:NO];
    IGAssertEqualPoint([self.collectionView contentOffset], 0, 0);
-    [self.adapter scrollToObject:@2 supplementaryKinds:@[UICollectionElementKindSectionHeader, UICollectionElementKindSectionFooter] scrollDirection:UICollectionViewScrollDirectionVertical animated:NO];
+    [self.adapter scrollToObject:@2 supplementaryKinds:@[UICollectionElementKindSectionHeader, UICollectionElementKindSectionFooter] scrollDirection:UICollectionViewScrollDirectionVertical scrollPosition:UICollectionViewScrollPositionNone animated:NO];
    IGAssertEqualPoint([self.collectionView contentOffset], 0, 30);
 }

@ -620,7 +628,7 @@ XCTAssertEqual(CGPointEqualToPoint(point, p), YES); \
    self.dataSource.objects = @[];
    [self.adapter reloadDataWithCompletion:nil];
    XCTAssertEqual([self.collectionView numberOfSections], 0);
-    [self.adapter scrollToObject:@1 supplementaryKinds:nil scrollDirection:UICollectionViewScrollDirectionVertical animated:NO];
+    [self.adapter scrollToObject:@1 supplementaryKinds:nil scrollDirection:UICollectionViewScrollDirectionVertical scrollPosition:UICollectionViewScrollPositionNone animated:NO];
    IGAssertEqualPoint([self.collectionView contentOffset], 0, 0);
 }

@ -629,13 +637,13 @@ XCTAssertEqual(CGPointEqualToPoint(point, p), YES); \
    self.dataSource.objects = @[@1, @2, @3, @4];
    [self.adapter reloadDataWithCompletion:nil];
    XCTAssertEqual([self.collectionView numberOfSections], 4);
-    [self.adapter scrollToObject:@1 supplementaryKinds:nil scrollDirection:UICollectionViewScrollDirectionVertical animated:NO];
+    [self.adapter scrollToObject:@1 supplementaryKinds:nil scrollDirection:UICollectionViewScrollDirectionVertical scrollPosition:UICollectionViewScrollPositionNone animated:NO];
    IGAssertEqualPoint([self.collectionView contentOffset], 0, 0);
-    [self.adapter scrollToObject:@5 supplementaryKinds:nil scrollDirection:UICollectionViewScrollDirectionVertical animated:NO];
+    [self.adapter scrollToObject:@5 supplementaryKinds:nil scrollDirection:UICollectionViewScrollDirectionVertical scrollPosition:UICollectionViewScrollPositionNone animated:NO];
    IGAssertEqualPoint([self.collectionView contentOffset], 0, 0);
-    [self.adapter scrollToObject:@2 supplementaryKinds:nil scrollDirection:UICollectionViewScrollDirectionVertical animated:NO];
+    [self.adapter scrollToObject:@2 supplementaryKinds:nil scrollDirection:UICollectionViewScrollDirectionVertical scrollPosition:UICollectionViewScrollPositionNone animated:NO];
    IGAssertEqualPoint([self.collectionView contentOffset], 0, 10);
-    [self.adapter scrollToObject:@5 supplementaryKinds:nil scrollDirection:UICollectionViewScrollDirectionVertical animated:NO];
+    [self.adapter scrollToObject:@5 supplementaryKinds:nil scrollDirection:UICollectionViewScrollDirectionVertical scrollPosition:UICollectionViewScrollPositionNone animated:NO];
    IGAssertEqualPoint([self.collectionView contentOffset], 0, 10);
 }