             metrics:metrics,
             views:views))
         addConstraints(NSLayoutConstraint.constraints(
-            withVisualFormat:"V:|-0-[spinner]-0-|",
+            withVisualFormat:"V:|-0-[spinner(headerHeight)]",
             options:[],
             metrics:metrics,
             views:views))

        { [weak self] in
            
            self?.spinner.stopAnimating()
            self?.collectionView.isHidden = false
        }
    }
    

            "collectionView":collectionView,
            "spinner":spinner]
        
        let metrics:[String:CGFloat] = [
            "headerHeight":kHeaderHeight]
        
        addConstraints(NSLayoutConstraint.constraints(
            withVisualFormat:"H:|-0-[collectionView]-0-|",
