#import "ASCollectionView.h"

#import "ASAssert.h"

#import "ASCollectionViewLayoutController.h"

#import "ASRangeController.h"

#import "ASCollectionDataController.h"

#import "ASDisplayNodeInternal.h"

#import "ASBatchFetching.h"

#import "UICollectionViewLayout+ASConvenience.h"

#import "ASInternalHelpers.h"

#import "ASCollectionViewFlowLayoutInspector.h"

#import "ASDisplayNode+Subclasses.h"

const static NSUInteger kASCollectionViewAnimationNone = UITableViewRowAnimationNone;

#pragma mark -

#pragma mark Proxying.

static BOOL _isInterceptedSelector(SEL sel)

{

return (

// handled by ASCollectionView node<->cell machinery

sel == @selector(collectionView:cellForItemAtIndexPath:) ||

sel == @selector(collectionView:layout:sizeForItemAtIndexPath:) ||

sel == @selector(collectionView:viewForSupplementaryElementOfKind:atIndexPath:) ||

// handled by ASRangeController

sel == @selector(numberOfSectionsInCollectionView:) ||

sel == @selector(collectionView:numberOfItemsInSection:) ||

// used for ASRangeController visibility updates

sel == @selector(collectionView:willDisplayCell:forItemAtIndexPath:) ||

sel == @selector(collectionView:didEndDisplayingCell:forItemAtIndexPath:) ||

// used for batch fetching API

sel == @selector(scrollViewWillEndDragging:withVelocity:targetContentOffset:)

);

}

@interface _ASCollectionViewProxy : NSProxy

- (instancetype)initWithTarget:(id<NSObject>)target interceptor:(ASCollectionView *)interceptor;

@implementation _ASCollectionViewProxy {

id<NSObject> __weak _target;

ASCollectionView * __weak _interceptor;

}

- (instancetype)initWithTarget:(id<NSObject>)target interceptor:(ASCollectionView *)interceptor

{

// -[NSProxy init] is undefined

if (!self) {

return nil;

}

ASDisplayNodeAssert(target, @"target must not be nil");

ASDisplayNodeAssert(interceptor, @"interceptor must not be nil");

_target = target;

_interceptor = interceptor;

return self;

}

- (BOOL)respondsToSelector:(SEL)aSelector

{

ASDisplayNodeAssert(_target, @"target must not be nil"); // catch weak ref's being nilled early

ASDisplayNodeAssert(_interceptor, @"interceptor must not be nil");

return (_isInterceptedSelector(aSelector) || [_target respondsToSelector:aSelector]);

}

- (id)forwardingTargetForSelector:(SEL)aSelector

{

ASDisplayNodeAssert(_target, @"target must not be nil"); // catch weak ref's being nilled early

ASDisplayNodeAssert(_interceptor, @"interceptor must not be nil");

if (_isInterceptedSelector(aSelector)) {

return _interceptor;

}

return [_target respondsToSelector:aSelector] ? _target : nil;

}

#pragma mark -

#pragma mark ASCellNode<->UICollectionViewCell bridging.

@class _ASCollectionViewCell;

@interface _ASCollectionViewCell : UICollectionViewCell

@property (nonatomic, weak) ASCellNode *node;

@implementation _ASCollectionViewCell

- (void)setSelected:(BOOL)selected

{

_node.selected = selected;

}

- (void)setHighlighted:(BOOL)highlighted

{

_node.highlighted = highlighted;

}

#pragma mark -

#pragma mark ASCollectionView.

@interface ASCollectionView () <ASRangeControllerDelegate, ASDataControllerSource> {

_ASCollectionViewProxy *_proxyDataSource;

_ASCollectionViewProxy *_proxyDelegate;

ASCollectionDataController *_dataController;

ASRangeController *_rangeController;

ASCollectionViewLayoutController *_layoutController;

ASCollectionViewFlowLayoutInspector *_flowLayoutInspector;

BOOL _performingBatchUpdates;

NSMutableArray *_batchUpdateBlocks;

BOOL _asyncDataFetchingEnabled;

BOOL _asyncDelegateImplementsInsetSection;

BOOL _collectionViewLayoutImplementsInsetSection;

BOOL _asyncDataSourceImplementsConstrainedSizeForNode;

ASBatchContext *_batchContext;

CGSize _maxSizeForNodesConstrainedSize;

BOOL _ignoreMaxSizeChange;

NSMutableArray *_registeredSupplementaryKinds;

/**

BOOL _superIsPendingDataLoad;

}

@property (atomic, assign) BOOL asyncDataSourceLocked;

@implementation ASCollectionView

#pragma mark -

#pragma mark Lifecycle.

- (instancetype)initWithCollectionViewLayout:(UICollectionViewLayout *)layout

{

return [self initWithFrame:CGRectZero collectionViewLayout:layout asyncDataFetching:NO];

}

- (instancetype)initWithFrame:(CGRect)frame collectionViewLayout:(UICollectionViewLayout *)layout

{

return [self initWithFrame:frame collectionViewLayout:layout asyncDataFetching:NO];

}

- (instancetype)initWithFrame:(CGRect)frame collectionViewLayout:(UICollectionViewLayout *)layout asyncDataFetching:(BOOL)asyncDataFetchingEnabled

{

if (!(self = [super initWithFrame:frame collectionViewLayout:layout]))

return nil;

// FIXME: asyncDataFetching is currently unreliable for some use cases.

// https://github.com/facebook/AsyncDisplayKit/issues/385

asyncDataFetchingEnabled = NO;

_layoutController = [[ASCollectionViewLayoutController alloc] initWithCollectionView:self];

_rangeController = [[ASRangeController alloc] init];

_rangeController.delegate = self;

_rangeController.layoutController = _layoutController;

_dataController = [[ASCollectionDataController alloc] initWithAsyncDataFetching:asyncDataFetchingEnabled];

_dataController.delegate = _rangeController;

_dataController.dataSource = self;

_batchContext = [[ASBatchContext alloc] init];

_leadingScreensForBatching = 1.0;

_asyncDataFetchingEnabled = asyncDataFetchingEnabled;

_asyncDataSourceLocked = NO;

_performingBatchUpdates = NO;

_batchUpdateBlocks = [NSMutableArray array];

_superIsPendingDataLoad = YES;

_collectionViewLayoutImplementsInsetSection = [layout respondsToSelector:@selector(sectionInset)];

_maxSizeForNodesConstrainedSize = self.bounds.size;

// If the initial size is 0, expect a size change very soon which is part of the initial configuration

// and should not trigger a relayout.

_ignoreMaxSizeChange = CGSizeEqualToSize(_maxSizeForNodesConstrainedSize, CGSizeZero);

// Register the default layout inspector delegate for flow layouts only, custom layouts

// will need to roll their own ASCollectionViewLayoutInspecting implementation and set a layout delegate

if ([layout asdk_isFlowLayout]) {

_layoutDelegate = [self flowLayoutInspector];

}

_registeredSupplementaryKinds = [NSMutableArray array];

self.backgroundColor = [UIColor whiteColor];

[self registerClass:[_ASCollectionViewCell class] forCellWithReuseIdentifier:@"_ASCollectionViewCell"];

return self;

}

- (void)dealloc

{

// Sometimes the UIKit classes can call back to their delegate even during deallocation.

// This bug might be iOS 7-specific.

super.delegate = nil;

super.dataSource = nil;

}

- (ASCollectionViewFlowLayoutInspector *)flowLayoutInspector

{

if (_flowLayoutInspector == nil) {

UICollectionViewFlowLayout *layout = (UICollectionViewFlowLayout *)self.collectionViewLayout;

_flowLayoutInspector = [[ASCollectionViewFlowLayoutInspector alloc] initWithCollectionView:self

flowLayout:layout];

}

return _flowLayoutInspector;

}

#pragma mark -

#pragma mark Overrides.

- (void)reloadDataWithCompletion:(void (^)())completion

{

ASDisplayNodeAssert(self.asyncDelegate, @"ASCollectionView's asyncDelegate property must be set.");

ASDisplayNodePerformBlockOnMainThread(^{

_superIsPendingDataLoad = YES;

[super reloadData];

});

[_dataController reloadDataWithAnimationOptions:kASCollectionViewAnimationNone completion:completion];

}

- (void)reloadData

{

[self reloadDataWithCompletion:nil];

}

- (void)setDataSource:(id<UICollectionViewDataSource>)dataSource

{

// UIKit can internally generate a call to this method upon changing the asyncDataSource; only assert for non-nil.

ASDisplayNodeAssert(dataSource == nil, @"ASCollectionView uses asyncDataSource, not UICollectionView's dataSource property.");

}

- (void)setDelegate:(id<UICollectionViewDelegate>)delegate

{

// Our UIScrollView superclass sets its delegate to nil on dealloc. Only assert if we get a non-nil value here.

ASDisplayNodeAssert(delegate == nil, @"ASCollectionView uses asyncDelegate, not UICollectionView's delegate property.");

}

- (void)setAsyncDataSource:(id<ASCollectionViewDataSource>)asyncDataSource

{

// Note: It's common to check if the value hasn't changed and short-circuit but we aren't doing that here to handle

// the (common) case of nilling the asyncDataSource in the ViewController's dealloc. In this case our _asyncDataSource

// will return as nil (ARC magic) even though the _proxyDataSource still exists. It's really important to nil out

// super.dataSource in this case because calls to _ASTableViewProxy will start failing and cause crashes.

if (asyncDataSource == nil) {

super.dataSource = nil;

_asyncDataSource = nil;

_proxyDataSource = nil;

_asyncDataSourceImplementsConstrainedSizeForNode = NO;

} else {

_asyncDataSource = asyncDataSource;

_proxyDataSource = [[_ASCollectionViewProxy alloc] initWithTarget:_asyncDataSource interceptor:self];

super.dataSource = (id<UICollectionViewDataSource>)_proxyDataSource;

_asyncDataSourceImplementsConstrainedSizeForNode = ([_asyncDataSource respondsToSelector:@selector(collectionView:constrainedSizeForNodeAtIndexPath:)] ? 1 : 0);

}

}

- (void)setAsyncDelegate:(id<ASCollectionViewDelegate>)asyncDelegate

{

// Note: It's common to check if the value hasn't changed and short-circuit but we aren't doing that here to handle

// the (common) case of nilling the asyncDelegate in the ViewController's dealloc. In this case our _asyncDelegate

// will return as nil (ARC magic) even though the _proxyDelegate still exists. It's really important to nil out

// super.delegate in this case because calls to _ASTableViewProxy will start failing and cause crashes.

if (asyncDelegate == nil) {

// order is important here, the delegate must be callable while nilling super.delegate to avoid random crashes

// in UIScrollViewAccessibility.

super.delegate = nil;

_asyncDelegate = nil;

_proxyDelegate = nil;

_asyncDelegateImplementsInsetSection = NO;

} else {

_asyncDelegate = asyncDelegate;

_proxyDelegate = [[_ASCollectionViewProxy alloc] initWithTarget:_asyncDelegate interceptor:self];

super.delegate = (id<UICollectionViewDelegate>)_proxyDelegate;

_asyncDelegateImplementsInsetSection = ([_asyncDelegate respondsToSelector:@selector(collectionView:layout:insetForSectionAtIndex:)] ? 1 : 0);

}

[_flowLayoutInspector cacheSelectorsForCollectionView:self];

}

- (void)setCollectionViewLayout:(UICollectionViewLayout *)collectionViewLayout

{

[super setCollectionViewLayout:collectionViewLayout];

if ([collectionViewLayout asdk_isFlowLayout]) {

_flowLayoutInspector = nil;

_layoutDelegate = [self flowLayoutInspector];

}

}

- (void)setTuningParameters:(ASRangeTuningParameters)tuningParameters forRangeType:(ASLayoutRangeType)rangeType

{

[_layoutController setTuningParameters:tuningParameters forRangeType:rangeType];

}

- (ASRangeTuningParameters)tuningParametersForRangeType:(ASLayoutRangeType)rangeType

{

return [_layoutController tuningParametersForRangeType:rangeType];

}

- (ASRangeTuningParameters)rangeTuningParameters

{

return [self tuningParametersForRangeType:ASLayoutRangeTypeRender];

}

- (void)setRangeTuningParameters:(ASRangeTuningParameters)tuningParameters

{

[self setTuningParameters:tuningParameters forRangeType:ASLayoutRangeTypeRender];

}

- (CGSize)calculatedSizeForNodeAtIndexPath:(NSIndexPath *)indexPath

{

return [[_dataController nodeAtIndexPath:indexPath] calculatedSize];

}

- (ASCellNode *)nodeForItemAtIndexPath:(NSIndexPath *)indexPath

{

return [_dataController nodeAtIndexPath:indexPath];

}

- (NSIndexPath *)indexPathForNode:(ASCellNode *)cellNode

{

return [_dataController indexPathForNode:cellNode];

}

- (NSArray *)visibleNodes

{

NSArray *indexPaths = [self indexPathsForVisibleItems];

NSMutableArray *visibleNodes = [[NSMutableArray alloc] init];

[indexPaths enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {

ASCellNode *visibleNode = [self nodeForItemAtIndexPath:obj];

[visibleNodes addObject:visibleNode];

}];

return visibleNodes;

}

#pragma mark Assertions.

- (void)performBatchAnimated:(BOOL)animated updates:(void (^)())updates completion:(void (^)(BOOL))completion

{

ASDisplayNodeAssertMainThread();

[_dataController beginUpdates];

updates();

[_dataController endUpdatesAnimated:animated completion:completion];

}

- (void)performBatchUpdates:(void (^)())updates completion:(void (^)(BOOL))completion

{

[self performBatchAnimated:YES updates:updates completion:completion];

}

- (void)registerSupplementaryNodeOfKind:(NSString *)elementKind

{

ASDisplayNodeAssert(elementKind != nil, @"A kind is needed for supplementary node registration");

[_registeredSupplementaryKinds addObject:elementKind];

[self registerClass:[UICollectionReusableView class] forSupplementaryViewOfKind:elementKind

withReuseIdentifier:[self __reuseIdentifierForKind:elementKind]];

}

- (void)insertSections:(NSIndexSet *)sections

{

ASDisplayNodeAssertMainThread();

[_dataController insertSections:sections withAnimationOptions:kASCollectionViewAnimationNone];

}

- (void)deleteSections:(NSIndexSet *)sections

{

ASDisplayNodeAssertMainThread();

[_dataController deleteSections:sections withAnimationOptions:kASCollectionViewAnimationNone];

}

- (void)reloadSections:(NSIndexSet *)sections

{

ASDisplayNodeAssertMainThread();

[_dataController reloadSections:sections withAnimationOptions:kASCollectionViewAnimationNone];

}

- (void)moveSection:(NSInteger)section toSection:(NSInteger)newSection

{

ASDisplayNodeAssertMainThread();

[_dataController moveSection:section toSection:newSection withAnimationOptions:kASCollectionViewAnimationNone];

}

- (void)insertItemsAtIndexPaths:(NSArray *)indexPaths

{

ASDisplayNodeAssertMainThread();

[_dataController insertRowsAtIndexPaths:indexPaths withAnimationOptions:kASCollectionViewAnimationNone];

}

- (void)deleteItemsAtIndexPaths:(NSArray *)indexPaths

{

ASDisplayNodeAssertMainThread();

[_dataController deleteRowsAtIndexPaths:indexPaths withAnimationOptions:kASCollectionViewAnimationNone];

}

- (void)reloadItemsAtIndexPaths:(NSArray *)indexPaths

{

ASDisplayNodeAssertMainThread();

[_dataController reloadRowsAtIndexPaths:indexPaths withAnimationOptions:kASCollectionViewAnimationNone];

}

- (void)moveItemAtIndexPath:(NSIndexPath *)indexPath toIndexPath:(NSIndexPath *)newIndexPath

{

ASDisplayNodeAssertMainThread();

[_dataController moveRowAtIndexPath:indexPath toIndexPath:newIndexPath withAnimationOptions:kASCollectionViewAnimationNone];

}

- (NSString *)__reuseIdentifierForKind:(NSString *)kind

{

return [@"_ASCollectionSupplementaryView_" stringByAppendingString:kind];

}

#pragma mark -

#pragma mark Intercepted selectors.

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath

{

static NSString *reuseIdentifier = @"_ASCollectionViewCell";

_ASCollectionViewCell *cell = [self dequeueReusableCellWithReuseIdentifier:reuseIdentifier forIndexPath:indexPath];

ASCellNode *node = [_dataController nodeAtIndexPath:indexPath];

[_rangeController configureContentView:cell.contentView forCellNode:node];

cell.node = node;

return cell;

}

- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath

{

return [[_dataController nodeAtIndexPath:indexPath] calculatedSize];

}

- (UICollectionReusableView *)collectionView:(UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath

{

NSString *identifier = [self __reuseIdentifierForKind:kind];

UICollectionReusableView *view = [self dequeueReusableSupplementaryViewOfKind:kind withReuseIdentifier:identifier forIndexPath:indexPath];

ASCellNode *node = [_dataController supplementaryNodeOfKind:kind atIndexPath:indexPath];

[_rangeController configureContentView:view forCellNode:node];

return view;

}

- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView

{

_superIsPendingDataLoad = NO;

return [_dataController numberOfSections];

}

- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section

{

return [_dataController numberOfRowsInSection:section];

}

- (ASScrollDirection)scrollDirection

{

CGPoint scrollVelocity = [self.panGestureRecognizer velocityInView:self.superview];

return [self scrollDirectionForVelocity:scrollVelocity];

}

- (ASScrollDirection)scrollDirectionForVelocity:(CGPoint)scrollVelocity

{

ASScrollDirection direction = ASScrollDirectionNone;

ASScrollDirection scrollableDirections = [self scrollableDirections];

if (ASScrollDirectionContainsHorizontalDirection(scrollableDirections)) { // Can scroll horizontally.

if (scrollVelocity.x >= 0) {

direction |= ASScrollDirectionRight;

} else {

direction |= ASScrollDirectionLeft;

}

}

if (ASScrollDirectionContainsVerticalDirection(scrollableDirections)) { // Can scroll vertically.

if (scrollVelocity.y >= 0) {

direction |= ASScrollDirectionDown;

} else {

direction |= ASScrollDirectionUp;

}

}

return direction;

}

- (ASScrollDirection)scrollableDirections

{

if ([self.collectionViewLayout asdk_isFlowLayout]) {

return [self flowLayoutScrollableDirections:(UICollectionViewFlowLayout *)self.collectionViewLayout];

} else {

return [self nonFlowLayoutScrollableDirections];

}

}

- (ASScrollDirection)flowLayoutScrollableDirections:(UICollectionViewFlowLayout *)flowLayout {

return (flowLayout.scrollDirection == UICollectionViewScrollDirectionHorizontal) ? ASScrollDirectionHorizontalDirections : ASScrollDirectionVerticalDirections;

}

- (ASScrollDirection)nonFlowLayoutScrollableDirections

{

ASScrollDirection scrollableDirection = ASScrollDirectionNone;

if (self.contentSize.width > self.bounds.size.width) { // Can scroll horizontally.

scrollableDirection |= ASScrollDirectionHorizontalDirections;

}

if (self.contentSize.height > self.bounds.size.height) { // Can scroll vertically.

scrollableDirection |= ASScrollDirectionVerticalDirections;

}

return scrollableDirection;

}

- (void)collectionView:(UICollectionView *)collectionView willDisplayCell:(UICollectionViewCell *)cell forItemAtIndexPath:(NSIndexPath *)indexPath

{

[_rangeController visibleNodeIndexPathsDidChangeWithScrollDirection:self.scrollDirection];

if ([_asyncDelegate respondsToSelector:@selector(collectionView:willDisplayNodeForItemAtIndexPath:)]) {

[_asyncDelegate collectionView:self willDisplayNodeForItemAtIndexPath:indexPath];

}

ASCellNode *cellNode = [self nodeForItemAtIndexPath:indexPath];

if (cellNode.neverShowPlaceholders) {

[cellNode recursivelyEnsureDisplay];

}

}

- (void)collectionView:(UICollectionView *)collectionView didEndDisplayingCell:(UICollectionViewCell *)cell forItemAtIndexPath:(NSIndexPath *)indexPath

{

[_rangeController visibleNodeIndexPathsDidChangeWithScrollDirection:self.scrollDirection];

if ([_asyncDelegate respondsToSelector:@selector(collectionView:didEndDisplayingNodeForItemAtIndexPath:)]) {

[_asyncDelegate collectionView:self didEndDisplayingNodeForItemAtIndexPath:indexPath];

}

}

- (void)layoutSubviews

{

if (! CGSizeEqualToSize(_maxSizeForNodesConstrainedSize, self.bounds.size)) {

_maxSizeForNodesConstrainedSize = self.bounds.size;

// First size change occurs during initial configuration. An expensive relayout pass is unnecessary at that time

// and should be avoided, assuming that the initial data loading automatically runs shortly afterward.

if (_ignoreMaxSizeChange) {

_ignoreMaxSizeChange = NO;

} else {

[self performBatchAnimated:NO updates:^{

[_dataController relayoutAllNodes];

} completion:nil];

}

}

// To ensure _maxSizeForNodesConstrainedSize is up-to-date for every usage, this call to super must be done last

[super layoutSubviews];

}

#pragma mark -

#pragma mark Batch Fetching

- (void)scrollViewWillEndDragging:(UIScrollView *)scrollView withVelocity:(CGPoint)velocity targetContentOffset:(inout CGPoint *)targetContentOffset

{

[self handleBatchFetchScrollingToOffset:*targetContentOffset];

if ([_asyncDelegate respondsToSelector:@selector(scrollViewWillEndDragging:withVelocity:targetContentOffset:)]) {

[_asyncDelegate scrollViewWillEndDragging:scrollView withVelocity:velocity targetContentOffset:targetContentOffset];

}

}

- (BOOL)shouldBatchFetch

{

// if the delegate does not respond to this method, there is no point in starting to fetch

BOOL canFetch = [_asyncDelegate respondsToSelector:@selector(collectionView:willBeginBatchFetchWithContext:)];

if (canFetch && [_asyncDelegate respondsToSelector:@selector(shouldBatchFetchForCollectionView:)]) {

return [_asyncDelegate shouldBatchFetchForCollectionView:self];

} else {

return canFetch;

}

}

- (void)handleBatchFetchScrollingToOffset:(CGPoint)targetOffset

{

ASDisplayNodeAssert(_batchContext != nil, @"Batch context should exist");

if (![self shouldBatchFetch]) {

return;

}

if (ASDisplayShouldFetchBatchForContext(_batchContext, [self scrollDirection], self.bounds, self.contentSize, targetOffset, _leadingScreensForBatching)) {

[_batchContext beginBatchFetching];

dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{

[_asyncDelegate collectionView:self willBeginBatchFetchWithContext:_batchContext];

});

}

}

#pragma mark - ASDataControllerSource

- (ASCellNode *)dataController:(ASDataController *)dataController nodeAtIndexPath:(NSIndexPath *)indexPath

{

ASCellNode *node = [_asyncDataSource collectionView:self nodeForItemAtIndexPath:indexPath];

ASDisplayNodeAssert([node isKindOfClass:ASCellNode.class], @"invalid node class, expected ASCellNode");

return node;

}

- (ASSizeRange)dataController:(ASDataController *)dataController constrainedSizeForNodeAtIndexPath:(NSIndexPath *)indexPath

{

ASSizeRange constrainedSize;

if (_asyncDataSourceImplementsConstrainedSizeForNode) {

constrainedSize = [_asyncDataSource collectionView:self constrainedSizeForNodeAtIndexPath:indexPath];

} else {

CGSize maxSize = _maxSizeForNodesConstrainedSize;

if (ASScrollDirectionContainsHorizontalDirection([self scrollableDirections])) {

maxSize.width = FLT_MAX;

} else {

maxSize.height = FLT_MAX;

}

constrainedSize = ASSizeRangeMake(CGSizeZero, maxSize);

}

UIEdgeInsets sectionInset = UIEdgeInsetsZero;

if (_collectionViewLayoutImplementsInsetSection) {

sectionInset = [(UICollectionViewFlowLayout *)self.collectionViewLayout sectionInset];

}

if (_asyncDelegateImplementsInsetSection) {

sectionInset = [(id<ASCollectionViewDelegateFlowLayout>)_asyncDelegate collectionView:self layout:self.collectionViewLayout insetForSectionAtIndex:indexPath.section];

}

if (ASScrollDirectionContainsHorizontalDirection([self scrollableDirections])) {

constrainedSize.min.width = MAX(0, constrainedSize.min.width - sectionInset.left - sectionInset.right);

//ignore insets for FLT_MAX so FLT_MAX can be compared against

if (constrainedSize.max.width - FLT_EPSILON < FLT_MAX) {

constrainedSize.max.width = MAX(0, constrainedSize.max.width - sectionInset.left - sectionInset.right);

}

} else {

constrainedSize.min.height = MAX(0, constrainedSize.min.height - sectionInset.top - sectionInset.bottom);

//ignore insets for FLT_MAX so FLT_MAX can be compared against

if (constrainedSize.max.height - FLT_EPSILON < FLT_MAX) {

constrainedSize.max.height = MAX(0, constrainedSize.max.height - sectionInset.top - sectionInset.bottom);

}

}

return constrainedSize;

}

- (NSUInteger)dataController:(ASDataController *)dataController rowsInSection:(NSUInteger)section

{

return [_asyncDataSource collectionView:self numberOfItemsInSection:section];

}

- (NSUInteger)numberOfSectionsInDataController:(ASDataController *)dataController {

if ([_asyncDataSource respondsToSelector:@selector(numberOfSectionsInCollectionView:)]) {

return [_asyncDataSource numberOfSectionsInCollectionView:self];

} else {

return 1;

}

}

- (void)dataControllerLockDataSource

{

ASDisplayNodeAssert(!self.asyncDataSourceLocked, @"The data source has already been locked");

self.asyncDataSourceLocked = YES;

if ([_asyncDataSource respondsToSelector:@selector(collectionViewLockDataSource:)]) {

[_asyncDataSource collectionViewLockDataSource:self];

}

}

- (void)dataControllerUnlockDataSource

{

ASDisplayNodeAssert(self.asyncDataSourceLocked, @"The data source has already been unlocked");

self.asyncDataSourceLocked = NO;

if ([_asyncDataSource respondsToSelector:@selector(collectionViewUnlockDataSource:)]) {

[_asyncDataSource collectionViewUnlockDataSource:self];

}

}

#pragma mark - ASCollectionViewDataControllerSource Supplementary view support

- (ASCellNode *)dataController:(ASCollectionDataController *)dataController supplementaryNodeOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath

{

ASCellNode *node = [_asyncDataSource collectionView:self nodeForSupplementaryElementOfKind:kind atIndexPath:indexPath];

ASDisplayNodeAssert(node != nil, @"A node must be returned for a supplementary node");

return node;

}

- (NSArray *)supplementaryNodeKindsInDataController:(ASCollectionDataController *)dataController

{

return _registeredSupplementaryKinds;

}

- (ASSizeRange)dataController:(ASCollectionDataController *)dataController constrainedSizeForSupplementaryNodeOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath

{

ASDisplayNodeAssert(_layoutDelegate != nil, @"To support supplementary nodes in ASCollectionView, it must have a layoutDelegate for layout inspection. (See ASCollectionViewFlowLayoutInspector for an example.)");

return [_layoutDelegate collectionView:self constrainedSizeForSupplementaryNodeOfKind:kind atIndexPath:indexPath];

}

- (NSUInteger)dataController:(ASCollectionDataController *)dataController supplementaryNodesOfKind:(NSString *)kind inSection:(NSUInteger)section

{

ASDisplayNodeAssert(_layoutDelegate != nil, @"To support supplementary nodes in ASCollectionView, it must have a layoutDelegate for layout inspection. (See ASCollectionViewFlowLayoutInspector for an example.)");

return [_layoutDelegate collectionView:self supplementaryNodesOfKind:kind inSection:section];

}

- (NSUInteger)dataController:(ASCollectionDataController *)dataController numberOfSectionsForSupplementaryNodeOfKind:(NSString *)kind;

{

ASDisplayNodeAssert(_layoutDelegate != nil, @"To support supplementary nodes in ASCollectionView, it must have a layoutDelegate for layout inspection. (See ASCollectionViewFlowLayoutInspector for an example.)");

return [_layoutDelegate collectionView:self numberOfSectionsForSupplementaryNodeOfKind:kind];

}

#pragma mark - ASRangeControllerDelegate.

- (void)rangeControllerBeginUpdates:(ASRangeController *)rangeController {

ASDisplayNodeAssertMainThread();

_performingBatchUpdates = YES;

}

- (void)rangeController:(ASRangeController *)rangeController endUpdatesAnimated:(BOOL)animated completion:(void (^)(BOOL))completion {

ASDisplayNodeAssertMainThread();

if (!self.asyncDataSource || _superIsPendingDataLoad) {

if (completion) {

completion(NO);

}

return; // if the asyncDataSource has become invalid while we are processing, ignore this request to avoid crashes

}

BOOL animationsEnabled = NO;

if (!animated) {

animationsEnabled = [UIView areAnimationsEnabled];

[UIView setAnimationsEnabled:NO];

}

[super performBatchUpdates:^{

[_batchUpdateBlocks enumerateObjectsUsingBlock:^(dispatch_block_t block, NSUInteger idx, BOOL *stop) {

block();

}];

} completion:^(BOOL finished) {

if (!animated) {

[UIView setAnimationsEnabled:animationsEnabled];

}

if (completion) {

completion(finished);

}

}];

[_batchUpdateBlocks removeAllObjects];

_performingBatchUpdates = NO;

}

- (NSArray *)rangeControllerVisibleNodeIndexPaths:(ASRangeController *)rangeController

{

ASDisplayNodeAssertMainThread();

return [self indexPathsForVisibleItems];

}

- (CGSize)rangeControllerViewportSize:(ASRangeController *)rangeController

{

ASDisplayNodeAssertMainThread();

return self.bounds.size;

}

- (NSArray *)rangeController:(ASRangeController *)rangeController nodesAtIndexPaths:(NSArray *)indexPaths

{

return [_dataController nodesAtIndexPaths:indexPaths];

}

- (void)rangeController:(ASRangeController *)rangeController didInsertNodes:(NSArray *)nodes atIndexPaths:(NSArray *)indexPaths withAnimationOptions:(ASDataControllerAnimationOptions)animationOptions

{

ASDisplayNodeAssertMainThread();

if (!self.asyncDataSource || _superIsPendingDataLoad) {

return; // if the asyncDataSource has become invalid while we are processing, ignore this request to avoid crashes

}

if (_performingBatchUpdates) {

[_batchUpdateBlocks addObject:^{

[super insertItemsAtIndexPaths:indexPaths];

}];

} else {

[UIView performWithoutAnimation:^{

[super insertItemsAtIndexPaths:indexPaths];

}];

}

}

- (void)rangeController:(ASRangeController *)rangeController didDeleteNodes:(NSArray *)nodes atIndexPaths:(NSArray *)indexPaths withAnimationOptions:(ASDataControllerAnimationOptions)animationOptions

{

ASDisplayNodeAssertMainThread();

if (!self.asyncDataSource || _superIsPendingDataLoad) {

return; // if the asyncDataSource has become invalid while we are processing, ignore this request to avoid crashes

}

if (_performingBatchUpdates) {

[_batchUpdateBlocks addObject:^{

[super deleteItemsAtIndexPaths:indexPaths];

}];

} else {

[UIView performWithoutAnimation:^{

[super deleteItemsAtIndexPaths:indexPaths];

}];

}

}

- (void)rangeController:(ASRangeController *)rangeController didInsertSectionsAtIndexSet:(NSIndexSet *)indexSet withAnimationOptions:(ASDataControllerAnimationOptions)animationOptions

{

ASDisplayNodeAssertMainThread();

if (!self.asyncDataSource || _superIsPendingDataLoad) {

return; // if the asyncDataSource has become invalid while we are processing, ignore this request to avoid crashes

}

if (_performingBatchUpdates) {

[_batchUpdateBlocks addObject:^{

[super insertSections:indexSet];

}];

} else {

[UIView performWithoutAnimation:^{

[super insertSections:indexSet];

}];

}

}

- (void)rangeController:(ASRangeController *)rangeController didDeleteSectionsAtIndexSet:(NSIndexSet *)indexSet withAnimationOptions:(ASDataControllerAnimationOptions)animationOptions

{

ASDisplayNodeAssertMainThread();

if (!self.asyncDataSource || _superIsPendingDataLoad) {

return; // if the asyncDataSource has become invalid while we are processing, ignore this request to avoid crashes

}

if (_performingBatchUpdates) {

[_batchUpdateBlocks addObject:^{

[super deleteSections:indexSet];

}];

} else {

[UIView performWithoutAnimation:^{

[super deleteSections:indexSet];

}];

}

}