设置collectionView sectionHeader 悬浮 （针对MVVM）
viewMode中设置多个sectionArray 并且为每个section 设置header
将sectionArray添加进 dataArray中 并返回dataArray
VC中设置layout
//section header 悬浮自定义layout
- (UICollectionViewLayout*)collectionViewLayout {
UICollectionViewLayout * layout = self.collectionView.collectionViewLayout;
if(!layout) {
UICollectionViewFlowLayout * flowLayout = [[UICollectionViewFlowLayout alloc] init];
flowLayout.scrollDirection = UICollectionViewScrollDirectionVertical;
flowLayout.minimumLineSpacing=10;
flowLayout.minimumInteritemSpacing = 0;
flowLayout.sectionInset = UIEdgeInsetsZero;
flowLayout.headerReferenceSize = CGSizeZero;
flowLayout.footerReferenceSize = CGSizeZero;
if(IOS_9_OR_LATER()){
flowLayout.sectionHeadersPinToVisibleBounds = YES;
}
layout = flowLayout;
}
returnlayout;
}
