`minimumColumnSpacing` is ambiguous in Swift and Objective-C version

[HY558]

Objective-C:

- (CGFloat)itemWidthInSectionAtIndex:(NSInteger)section {
  UIEdgeInsets sectionInset;
  if ([self.delegate respondsToSelector:@selector(collectionView:layout:insetForSectionAtIndex:)]) {
    sectionInset = [self.delegate collectionView:self.collectionView layout:self insetForSectionAtIndex:section];
  } else {
    sectionInset = self.sectionInset;
  }
  CGFloat width = self.collectionView.bounds.size.width - sectionInset.left - sectionInset.right;
  NSInteger columnCount = [self columnCountForSection:section];

  CGFloat columnSpacing = self.minimumColumnSpacing;
  if ([self.delegate respondsToSelector:@selector(collectionView:layout:minimumColumnSpacingForSectionAtIndex:)]) {
    columnSpacing = [self.delegate collectionView:self.collectionView layout:self minimumColumnSpacingForSectionAtIndex:section];
  }

  return CHTFloorCGFloat((width - (columnCount - 1) * columnSpacing) / columnCount);
}

Swift:

    public func itemWidth(inSection section: Int) -> CGFloat {
        let columnCount = self.columnCount(forSection: section)
        let spaceColumCount = CGFloat(columnCount - 1)
        let width = collectionViewContentWidth(ofSection: section)
        return floor((width - (spaceColumCount * minimumColumnSpacing)) / CGFloat(columnCount))
    }

In Swift version, collectionView:layout:minimumColumnSpacingForSectionAtIndex not be called in real time. minimumColumnSpacing for section not work.