UICollectionViewCell disappears in iOS 8 - ios

Question

I have a collectionView which works well in iOS 7 and now in iOS 8 is acts strangely.
when collectionView appears it only displays one cell: (it must be 2)
but after scrolling a bit the second cell appears
Im using a custom collectionViewFlowLayout. but changing to UICollectionViewFlowLayout doesn't fix the issue.
Cell Size : 657, 500
Min Spacing For Lines : 100
Min Spacing For Cells : 10
I have added left and right edge insets: (if I remove the insets it works well. but I must use insets to keep my cell at the center of view)
- (UIEdgeInsets)collectionView:(UICollectionView *)cv
layout:(UICollectionViewLayout *)cvl
insetForSectionAtIndex:(NSInteger)section {
return UIEdgeInsetsMake(0, (cv.bounds.size.width - 657) / 2.0f, 0,
(cv.bounds.size.width - 657) / 2.0f);
}
Here is my custom flow layout:
#import "CoverFlowLayout.h"
static const CGFloat kMaxDistancePercentage = 0.3f;
//static const CGFloat kMaxRotation = (CGFloat)(50.0 * (M_PI / 180.0));
static const CGFloat kMaxZoom = 0.1f;
#implementation CoverFlowLayout
- (id)init {
if ((self = [super init])) {
self.scrollDirection = UICollectionViewScrollDirectionHorizontal;
self.minimumLineSpacing = 10000.0f; }
return self;
}
- (NSArray*)layoutAttributesForElementsInRect:(CGRect)rect {
// 1
CGRect visibleRect =
(CGRect){.origin = self.collectionView.contentOffset,
.size = self.collectionView.bounds.size};
CGFloat maxDistance =
visibleRect.size.width * kMaxDistancePercentage;
// 2
NSArray *array = [super layoutAttributesForElementsInRect:rect];
for (UICollectionViewLayoutAttributes *attributes in array) {
// 3
CGFloat distance =
CGRectGetMidX(visibleRect) - attributes.center.x;
// 4
CGFloat normalizedDistance = distance / maxDistance;
normalizedDistance = MIN(normalizedDistance, 1.0f);
normalizedDistance = MAX(normalizedDistance, -1.0f);
// 5
//CGFloat rotation = normalizedDistance * kMaxRotation;
CGFloat zoom = 1.0f + ((1.0f - ABS(normalizedDistance)) * kMaxZoom);
// 6
CATransform3D transform = CATransform3DIdentity;
transform.m34 = 1.0 / -1000.0;
//transform = CATransform3DRotate(transform,
// rotation, 0.0f, 1.0f, 0.0f);
transform = CATransform3DScale(transform, zoom, zoom, zoom);
attributes.transform3D = transform;
}
// 7
return array;
}
- (BOOL)shouldInvalidateLayoutForBoundsChange:(CGRect)newBounds {
return YES;
}
- (CGPoint)targetContentOffsetForProposedContentOffset: (CGPoint)proposedContentOffset withScrollingVelocity:(CGPoint)velocity
{
// 1
CGFloat offsetAdjustment = CGFLOAT_MAX;
CGFloat horizontalCenter = proposedContentOffset.x +
(CGRectGetWidth(self.collectionView.bounds) / 2.0f);
// 2
CGRect targetRect = CGRectMake(proposedContentOffset.x,
0.0f, self.collectionView.bounds.size.width, self.collectionView.bounds.size.height);
NSArray *array =
[super layoutAttributesForElementsInRect:targetRect];
for (UICollectionViewLayoutAttributes* layoutAttributes in array)
{
// 3
CGFloat distanceFromCenter = layoutAttributes.center.x - horizontalCenter;
if (ABS(distanceFromCenter) < ABS(offsetAdjustment))
{
offsetAdjustment = distanceFromCenter;
}
}
// 4
return CGPointMake(proposedContentOffset.x + offsetAdjustment,
proposedContentOffset.y);
}
initially in overrided layoutAttributesForElementsInRect visible rect is {0,0, 1024, 768}
but [super layoutAttributesForElementsInRect:rect]; returns only one UICollectionViewCellAttribute. (it should be 2)
is any idea how can I fix this?

Answer 1

I don know How it can be cause of the issue but it was originated from:
NSIndexPath *visibleIndexPath = [self.collectionView indexPathForItemAtPoint:midPoint];
I want to update my pageControl to indicate which cell is at the center of screen.
I Changed my method and now it works well:
//*****updating page control*****
// get the visible rect
CGRect visibleRect = (CGRect) {.origin = self.collectionView.contentOffset,
.size = self.collectionView.bounds.size};
// get the mid point in the visible rect
CGPoint midPoint = CGPointMake(CGRectGetMidX(visibleRect), CGRectGetMidY(visibleRect));
// find indexPath of the item in that midPoint
//in iOS 8 Cause the second cell disappear
//NSIndexPath *visibleIndexPath = [self.collectionView indexPathForItemAtPoint:midPoint];
//iterating through visble cells to find the cell which contains midpoint then get get that cell indexpath
for (UICollectionViewCell *cell in [self.collectionView visibleCells]) {
if (CGRectContainsPoint(cell.frame, midPoint)) {
NSIndexPath *indexPath = [self.collectionView indexPathForCell:cell];
//update page control
self.pageControl.currentPage = indexPath.row;
//quiting loop
break;
}
}