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Proper support vertical and bottom positions in IGListAdapter scrollToObject: API

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Summary:
I simply wrote failing tests for `scrollToObject` API for the `ScrollPosition` parameter and then fixed the code.

If we agree that these tests are correct, I don't mind suggesting a fix for it. I think it's the `indexPath`'s row that is hardcoded to `0` that needs to be changed depending on the `scrollPosition` desired. (Done!)

- [x] All tests pass. Demo project builds and runs.
- [x] I added tests, an experiment, or detailed why my change isn't tested.
- [x] I added an entry to the `CHANGELOG.md` for any breaking changes, enhancements, or bug fixes.
- [x] I have reviewed the [contributing guide](https://github.com/Instagram/IGListKit/blob/master/.github/CONTRIBUTING.md)
Closes https://github.com/Instagram/IGListKit/pull/861

Differential Revision: D5678607

Pulled By: rnystrom

fbshipit-source-id: ab902b58fe70667ef6133cb05569a2223a668243
This commit is contained in:
Gulam Moledina 2017-08-22 13:25:56 -07:00 committed by Facebook Github Bot
parent 1fccfce0f1
commit f79516ee66
3 changed files with 46 additions and 10 deletions
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3
CHANGELOG.md
View file

@ -16,8 +16,11 @@ The changelog for `IGListKit`. Also see the [releases](https://github.com/instag
- Return correct `-[IGListAdapter visibleSectionControllers]` when section has no items, but has supplementary views. [Mani Ghasemlou](https://github.com/manicakes) [(#643)](https://github.com/Instagram/IGListKit/issues/643)
- Call `[CATransaction commit]` before calling completion block in IGListAdapterUpdater to prevent animation issues. [Maxime Ollivier](https://github.com/maxoll) (tbd)
- Fix `scrollToObject:supplementaryKinds:...` not scrolling when section is empty but does have supplymentary views
- Better support for non-top positions in `scrollToObject:` API. [Gulam Moledina](https://github.com/gmoledina) [(#861)](https://github.com/Instagram/IGListKit/pull/861)
### Enhancements
- Added `-[IGListSectionController didDeselectItemAtIndex:]` API to support default `UICollectionView` cell deselection. [Ryan Nystrom](https://github.com/rnystrom) (tbd)

20
Source/IGListAdapter.m
View file

@ -185,19 +185,27 @@
[collectionView setNeedsLayout];
[collectionView layoutIfNeeded];
NSIndexPath *indexPath = [NSIndexPath indexPathForItem:0 inSection:section];
NSIndexPath *indexPathFirstElement = [NSIndexPath indexPathForItem:0 inSection:section];
// collect the layout attributes for the cell and supplementary views for the first index
// this will break if there are supplementary views beyond item 0
NSArray *attributes = nil;
NSMutableArray<UICollectionViewLayoutAttributes *> *attributes = nil;
const NSInteger numberOfItems = [collectionView numberOfItemsInSection:section];
if (numberOfItems > 0) {
attributes = [self layoutAttributesForIndexPath:indexPath supplementaryKinds:supplementaryKinds];
attributes = [self layoutAttributesForIndexPath:indexPathFirstElement supplementaryKinds:supplementaryKinds].mutableCopy;
if (numberOfItems > 1) {
NSIndexPath *indexPathLastElement = [NSIndexPath indexPathForItem:(numberOfItems - 1) inSection:section];
UICollectionViewLayoutAttributes *lastElementattributes = [self layoutAttributesForIndexPath:indexPathLastElement supplementaryKinds:supplementaryKinds].firstObject;
if (lastElementattributes != nil) {
[attributes addObject:lastElementattributes];
}
}
} else {
NSMutableArray *supplementaryAttributes = [NSMutableArray new];
for (NSString* supplementaryKind in supplementaryKinds) {
UICollectionViewLayoutAttributes *supplementaryAttribute = [layout layoutAttributesForSupplementaryViewOfKind:supplementaryKind atIndexPath:indexPath];
UICollectionViewLayoutAttributes *supplementaryAttribute = [layout layoutAttributesForSupplementaryViewOfKind:supplementaryKind atIndexPath:indexPathFirstElement];
if (supplementaryAttribute != nil) {
[supplementaryAttributes addObject: supplementaryAttribute];
}

33
Tests/IGListAdapterTests.m
View file

@ -647,9 +647,9 @@
// Content height minus collection view height is 110, can't scroll more than that
IGAssertEqualPoint([self.collectionView contentOffset], 0, 110);
[self.adapter scrollToObject:@6 supplementaryKinds:nil scrollDirection:UICollectionViewScrollDirectionVertical scrollPosition:UICollectionViewScrollPositionCenteredVertically animated:NO];
IGAssertEqualPoint([self.collectionView contentOffset], 0, 105);
IGAssertEqualPoint([self.collectionView contentOffset], 0, 110);
[self.adapter scrollToObject:@6 supplementaryKinds:nil scrollDirection:UICollectionViewScrollDirectionVertical scrollPosition:UICollectionViewScrollPositionBottom animated:NO];
IGAssertEqualPoint([self.collectionView contentOffset], 0, 60);
IGAssertEqualPoint([self.collectionView contentOffset], 0, 110);
}
- (void)test_whenScrollVerticallyToItemInASectionWithNoCellsAndNoSupplymentaryView {
@ -689,6 +689,31 @@
IGAssertEqualPoint([self.collectionView contentOffset], 0, 20);
}
- (void)test_whenScrollVerticallyToItemWithPositionning {
self.dataSource.objects = @[@1, @100, @200];
[self.adapter reloadDataWithCompletion:nil];
[self.adapter scrollToObject:@1 supplementaryKinds:nil scrollDirection:UICollectionViewScrollDirectionVertical scrollPosition:UICollectionViewScrollPositionNone animated:NO];
IGAssertEqualPoint([self.collectionView contentOffset], 0, 0);
[self.adapter scrollToObject:@1 supplementaryKinds:nil scrollDirection:UICollectionViewScrollDirectionVertical scrollPosition:UICollectionViewScrollPositionTop animated:NO];
IGAssertEqualPoint([self.collectionView contentOffset], 0, 0);
[self.adapter scrollToObject:@1 supplementaryKinds:nil scrollDirection:UICollectionViewScrollDirectionVertical scrollPosition:UICollectionViewScrollPositionCenteredVertically animated:NO];
IGAssertEqualPoint([self.collectionView contentOffset], 0, 0);
[self.adapter scrollToObject:@1 supplementaryKinds:nil scrollDirection:UICollectionViewScrollDirectionVertical scrollPosition:UICollectionViewScrollPositionBottom animated:NO];
IGAssertEqualPoint([self.collectionView contentOffset], 0, 0);
[self.adapter scrollToObject:@100 supplementaryKinds:nil scrollDirection:UICollectionViewScrollDirectionVertical scrollPosition:UICollectionViewScrollPositionNone animated:NO];
IGAssertEqualPoint([self.collectionView contentOffset], 0, 10);
[self.adapter scrollToObject:@100 supplementaryKinds:nil scrollDirection:UICollectionViewScrollDirectionVertical scrollPosition:UICollectionViewScrollPositionTop animated:NO];
IGAssertEqualPoint([self.collectionView contentOffset], 0, 10);
[self.adapter scrollToObject:@100 supplementaryKinds:nil scrollDirection:UICollectionViewScrollDirectionVertical scrollPosition:UICollectionViewScrollPositionCenteredVertically animated:NO];
IGAssertEqualPoint([self.collectionView contentOffset], 0, 460);
[self.adapter scrollToObject:@100 supplementaryKinds:nil scrollDirection:UICollectionViewScrollDirectionVertical scrollPosition:UICollectionViewScrollPositionBottom animated:NO];
IGAssertEqualPoint([self.collectionView contentOffset], 0, 910);
[self.adapter scrollToObject:@200 supplementaryKinds:nil scrollDirection:UICollectionViewScrollDirectionVertical scrollPosition:UICollectionViewScrollPositionBottom animated:NO];
IGAssertEqualPoint([self.collectionView contentOffset], 0, self.collectionView.contentSize.height - self.collectionView.frame.size.height);
}
- (void)test_whenScrollHorizontallyToItem {
// # of items for each object == [item integerValue], so @2 has 2 items (cells)
IGListTestAdapterHorizontalDataSource *dataSource = [[IGListTestAdapterHorizontalDataSource alloc] init];
@ -707,9 +732,9 @@
// Content width minus collection view width is 110, can't scroll more than that
IGAssertEqualPoint([self.collectionView contentOffset], 110, 0);
[self.adapter scrollToObject:@6 supplementaryKinds:nil scrollDirection:UICollectionViewScrollDirectionHorizontal scrollPosition:UICollectionViewScrollPositionCenteredHorizontally animated:NO];
IGAssertEqualPoint([self.collectionView contentOffset], 105, 0);
IGAssertEqualPoint([self.collectionView contentOffset], 110, 0);
[self.adapter scrollToObject:@6 supplementaryKinds:nil scrollDirection:UICollectionViewScrollDirectionHorizontal scrollPosition:UICollectionViewScrollPositionRight animated:NO];
IGAssertEqualPoint([self.collectionView contentOffset], 60, 0);
IGAssertEqualPoint([self.collectionView contentOffset], 110, 0);
self.layout.scrollDirection = UICollectionViewScrollDirectionVertical;
self.adapter.dataSource = self.dataSource;
}