Modify the code in the CustomCollectionView Demo, hoping to achieve the preload function. But runtime has been call willBeginBatchFetchWithContext method to add new data

[xyl-private]

Hello, I modified the code in the CustomCollectionView Demo here, hoping to achieve the preload function. But running will keep call - (void)collectionNode:(ASCollectionNode *)collectionNode willBeginBatchFetchWithContext:(ASBatchContext *)context method to add new data, only when CollectionNode sliding will stop calling, trouble to help have a look.

#import "ViewController.h"

#import <AsyncDisplayKit/AsyncDisplayKit.h>
#import <AsyncDisplayKit/ASCollectionNode+Beta.h>
#import "MosaicCollectionLayoutDelegate.h"
#import "ImageCellNode.h"
#import "ImageCollectionViewCell.h"
#import "NetworkImageNode.h"

// This option demonstrates that raw UIKit cells can still be used alongside native ASCellNodes.
static BOOL kShowUICollectionViewCells = YES;
static NSString *kReuseIdentifier = @"ImageCollectionViewCell";
static NSUInteger kNumberOfImages = 14;

@interface ViewController () <ASCollectionDataSourceInterop, ASCollectionDelegate, ASCollectionViewLayoutInspecting>
{
  ASCollectionNode *_collectionNode;
}

@property (nonatomic, strong) NSMutableArray *list;

@end

@implementation ViewController

#pragma mark -
#pragma mark UIViewController

- (instancetype)init
{
  MosaicCollectionLayoutDelegate *layoutDelegate = [[MosaicCollectionLayoutDelegate alloc] initWithNumberOfColumns:2 headerHeight:0];
  _collectionNode = [[ASCollectionNode alloc] initWithLayoutDelegate:layoutDelegate layoutFacilitator:nil];
  _collectionNode.dataSource = self;
  _collectionNode.delegate = self;
  _collectionNode.leadingScreensForBatching = 2;
  //  _collectionNode.layoutInspector = self;

  if (!(self = [super initWithNode:_collectionNode]))
    return nil;

  self.list = [NSMutableArray array];
  for (NSUInteger idx = 0; idx < kNumberOfImages; idx++) {
    NSString *name = [NSString stringWithFormat:@"image_%lu.jpg", (unsigned long)idx];
    [self.list addObject:[UIImage imageNamed:name]];
  }

  return self;
}

- (void)viewDidLoad {
  [super viewDidLoad];

}

#pragma mark - ASCollectionNode data source.

- (ASCellNodeBlock)collectionNode:(ASCollectionNode *)collectionNode nodeBlockForItemAtIndexPath:(NSIndexPath *)indexPath {

  UIImage *image = self.list[indexPath.item];
  return ^{
    return [[ImageCellNode alloc] initWithImage:image];
  };
}

- (NSInteger)collectionNode:(ASCollectionNode *)collectionNode numberOfItemsInSection:(NSInteger)section {
  return self.list.count;
}

/// 接收到一个消息，说明tableView的数据集接近尾声，如果需要，应该获取更多的数据。
- (void)collectionNode:(ASCollectionNode *)collectionNode willBeginBatchFetchWithContext:(ASBatchContext *)context {
  NSLog(@"willBeginBatchFetchWithContext");

  NSMutableArray *newArr = [NSMutableArray array];
  for (NSUInteger idx = 0; idx < kNumberOfImages; idx++) {
    NSString *name = [NSString stringWithFormat:@"image_%lu.jpg", (unsigned long)idx];
    [newArr addObject:[UIImage imageNamed:name]];
  }
  dispatch_async(dispatch_get_main_queue(), ^{
    [self insertNewRowsInTableView:newArr];
    if (context) {
      [context completeBatchFetching:YES];
    }  
  });

}

- (void)insertNewRowsInTableView:(NSArray *)newAnimals {
  NSInteger oldCount = self.list.count;
  [self.list addObjectsFromArray:newAnimals];
  [self insertRowWithStart:oldCount NewCount:self.list.count];
}

/// 插入 Row
- (void)insertRowWithStart:(NSInteger)start NewCount:(NSInteger)count{
  NSInteger section = 0;
  NSMutableArray *indexPaths = [NSMutableArray array];
  for (NSUInteger row = start; row < count; row++) {
    NSIndexPath *path = [NSIndexPath indexPathForRow:row inSection:section];
    [indexPaths addObject:path];

  }
  [_collectionNode insertItemsAtIndexPaths:indexPaths];
}

@end