UICollectionView flowLayout not wrapping cells correctly

by

There is a bug in UICollectionViewFlowLayout’s implementation of layoutAttributesForElementsInRect that causes it to return TWO attribute objects for a single cell in certain cases involving section insets. One of the returned attribute objects is invalid (outside the bounds of the collection view) and the other is valid. Below is a subclass of UICollectionViewFlowLayout that fixes the problem by excluding cells outside of the collection view’s bounds.

// NDCollectionViewFlowLayout.h
@interface NDCollectionViewFlowLayout : UICollectionViewFlowLayout
@end

// NDCollectionViewFlowLayout.m
#import "NDCollectionViewFlowLayout.h"
@implementation NDCollectionViewFlowLayout
- (NSArray *)layoutAttributesForElementsInRect:(CGRect)rect {
  NSArray *attributes = [super layoutAttributesForElementsInRect:rect];
  NSMutableArray *newAttributes = [NSMutableArray arrayWithCapacity:attributes.count];
  for (UICollectionViewLayoutAttributes *attribute in attributes) {
    if ((attribute.frame.origin.x + attribute.frame.size.width <= self.collectionViewContentSize.width) &&
        (attribute.frame.origin.y + attribute.frame.size.height <= self.collectionViewContentSize.height)) {
      [newAttributes addObject:attribute];
    }
  }
  return newAttributes;
}
@end

See this.

Other answers suggest returning YES from shouldInvalidateLayoutForBoundsChange, but this causes unnecessary recomputations and doesn’t even completely solve the problem.

My solution completely solves the bug and shouldn’t cause any problems when Apple fixes the root cause.

More Related Contents:

  1. UICollectionView Self Sizing Cells with Auto Layout
  2. Dynamic cell width of UICollectionView depending on label width
  3. UICollectionView’s cell disappearing
  4. UICollectionView adding image to a cell
  5. UICollectionView Set number of columns
  6. Auto Layout in UICollectionViewCell not working
  7. UICollectionView Decoration View
  8. UICollectionView adding UICollectionCell
  9. Why on Xcode 11, UICollectionViewCell changes size as soon as you scroll (I already set size in sizeForItem AtIndexPath:)?
  10. UICollectionView update a single cell
  11. Make UICollectionView zoomable?
  12. Displaying images on another view controller when button is clicked
  13. How to make a simple collection view with Swift
  14. Is it possible to install iOS 6 SDK on Xcode 5?
  15. iOS 6: How do I restrict some views to portrait and allow others to rotate?
  16. Asynchronous downloading of images for UITableView with GCD
  17. Enabling auto layout in iOS 6 while remaining backwards compatible with iOS 5
  18. UICollectionView, full width cells, allow autolayout dynamic height?
  19. Tutorial for SLComposeViewController sharing [closed]
  20. What is the meaning of the “no index path for table cell being reused” message in iOS 6/7?
  21. is groupTableViewBackgroundColor deprecated on iOS 6?
  22. UICollectionView – Horizontal scroll, horizontal layout?
  23. UIButton in cell in collection view not receiving touch up inside event
  24. Facebook SDK 3.1 for iOS – runs on iOS6, but crashes on iOS 5.x
  25. UIRefreshControl on UICollectionView only works if the collection fills the height of the container
  26. Aligning right to left on UICollectionView
  27. UIRefreshControl with UICollectionView in iOS7
  28. Change UIImageView size to match image with AutoLayout
  29. Warning: UICollectionViewFlowLayout has cached frame mismatch for index path ‘abc’
  30. iOS Calendar Access Permission Dialog, force it to appear?

Leave a Comment