viewForSupplementaryElementOfKin

为了降低代码耦合性，通常自定义UICollectionViewFlowLayout。今天在自定义UICollectionViewFlowLayout时，想设置UICollectionView的footerView，但viewForSupplementaryElementOfKind不执行，改成系统的UICollectionViewFlowLayout就可以。

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自定义UICollectionViewFlowLayout添加header 和footer的解决方法：

- (nullableNSArray<__kindofUICollectionViewLayoutAttributes*> *)layoutAttributesForElementsInRect:(CGRect)rect{

NSMutableArray*attributes = [[superlayoutAttributesForElementsInRect:rect]mutableCopy];

for(NSIntegeri =0; i <_numberOfCells; i++) {

NSIndexPath*indexPath = [NSIndexPathindexPathForItem:iinSection:0];

UICollectionViewLayoutAttributes*attribute = [selflayoutAttributesForItemAtIndexPath:indexPath];

[attributesaddObject:attribute];

}

for(UICollectionViewLayoutAttributes*attrsinattributes) {

if([attrsrepresentedElementKind] ==UICollectionElementKindSectionFooter) {

CGRectheaderRect = [attrsframe];

headerRect.size.height=100;

headerRect.size.width=SCREEN_SIZE.width;

[attrssetFrame:headerRect];

break;

}

}

returnattributes;

}