如何在iOS7上的UICollectionView粘贴标题？
我使用这个解决scheme在集合视图中生成粘滞标题，它在iOS6上运行良好。 但是，在iOS7中，如果选中“在顶栏下方延伸边缘”选项，则标题将粘贴到位于导航栏后面的视图的原点。
所以现在我禁用了这个选项，但是我真的想调整这个解决scheme，使其在边缘扩展的时候能够工作（为了在内容在导航栏后面滚动时具有很好的模糊效果）。
有人可以帮我吗？ 还是有人有任何其他的build议来实现相同的目标？
这是我的完整解决scheme。 只需将以下内容添加到FlowLayout类中：
#pragma mark STICKY HEADERS CODE BELOW - (NSArray *)layoutAttributesForElementsInRect:(CGRect)rect { NSMutableArray *answer = [[super layoutAttributesForElementsInRect:rect] mutableCopy]; NSMutableIndexSet *missingSections = [NSMutableIndexSet indexSet]; for (NSUInteger idx=0; idx<[answer count]; idx++) { UICollectionViewLayoutAttributes *layoutAttributes = answer[idx]; if (layoutAttributes.representedElementCategory == UICollectionElementCategoryCell || layoutAttributes.representedElementCategory == UICollectionElementCategorySupplementaryView) { [missingSections addIndex:(NSUInteger) layoutAttributes.indexPath.section]; // remember that we need to layout header for this section } if ([layoutAttributes.representedElementKind isEqualToString:UICollectionElementKindSectionHeader]) { [answer removeObjectAtIndex:idx]; // remove layout of header done by our super, we will do it right later idx--; } } // layout all headers needed for the rect using self code [missingSections enumerateIndexesUsingBlock:^(NSUInteger idx, BOOL *stop) { NSIndexPath *indexPath = [NSIndexPath indexPathForItem:0 inSection:idx]; UICollectionViewLayoutAttributes *layoutAttributes = [self layoutAttributesForSupplementaryViewOfKind:UICollectionElementKindSectionHeader atIndexPath:indexPath]; if (layoutAttributes) { [answer addObject:layoutAttributes]; } }]; return answer; } - (UICollectionViewLayoutAttributes *)layoutAttributesForSupplementaryViewOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath { UICollectionViewLayoutAttributes *attributes = [super layoutAttributesForSupplementaryViewOfKind:kind atIndexPath:indexPath]; if ([kind isEqualToString:UICollectionElementKindSectionHeader]) { UICollectionView * const cv = self.collectionView; CGFloat topOffset = 0; if ([self.collectionView.dataSource isKindOfClass:[UIViewController class]]) { UIViewController *collectionViewParentViewController = (UIViewController *)self.collectionView.dataSource; topOffset = collectionViewParentViewController.topLayoutGuide.length; } CGPoint const contentOffset = CGPointMake(cv.contentOffset.x, cv.contentOffset.y + topOffset); CGPoint nextHeaderOrigin = CGPointMake(INFINITY, INFINITY); if (indexPath.section+1 < [cv numberOfSections]) { UICollectionViewLayoutAttributes *nextHeaderAttributes = [super layoutAttributesForSupplementaryViewOfKind:kind atIndexPath:[NSIndexPath indexPathForItem:0 inSection:indexPath.section+1]]; nextHeaderOrigin = nextHeaderAttributes.frame.origin; } CGRect frame = attributes.frame; if (self.scrollDirection == UICollectionViewScrollDirectionVertical) { frame.origin.y = MIN(MAX(contentOffset.y, frame.origin.y), nextHeaderOrigin.y - CGRectGetHeight(frame)); } else { frame.origin.x = MIN(MAX(contentOffset.x, frame.origin.x), nextHeaderOrigin.x - CGRectGetWidth(frame)); } attributes.zIndex = 1024; attributes.frame = frame; } return attributes; } - (UICollectionViewLayoutAttributes *)initialLayoutAttributesForAppearingSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath { UICollectionViewLayoutAttributes *attributes = [self layoutAttributesForSupplementaryViewOfKind:kind atIndexPath:indexPath]; return attributes; } - (UICollectionViewLayoutAttributes *)finalLayoutAttributesForDisappearingSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath { UICollectionViewLayoutAttributes *attributes = [self layoutAttributesForSupplementaryViewOfKind:kind atIndexPath:indexPath]; return attributes; } - (BOOL)shouldInvalidateLayoutForBoundsChange:(CGRect)newBound { return YES; }