Dynamic updating of UITableView with FireStore changes.

DynamicFireStoreTableView.swift

func dataSourceForQuery(_ query: Query) -> CategorySessionsTableViewDataSource {
        return CategorySessionsTableViewDataSource(query: query) { (changes, sessions) in
            
            // Success: Perform batch remove / insert of cells
            if #available(iOS 11.0, *) {
                self.tableView.performBatchUpdates({
                    self.performUpdates(for: changes)
                }, completion: nil)
            }

            // Fallback on earlier versions
            else {
                self.tableView.beginUpdates()
                self.performUpdates(for: changes)
                self.tableView.endUpdates()
            }

            // Dismiss Activity Loader
            self.dismissActivity()
        }
    }
    
    /// Performs needed UI updates based on `DocumentChange`'s in TableView
    fileprivate func performUpdates(for changes: [DocumentChange]) {
        guard let totalRowCount = self.dataSource?.count else {
            return
        }
        changes.forEach { (change) in
            switch change.type {
            case .added:
                
                // Only insert if needed
                if self.tableView.numberOfRows(inSection: 0) < totalRowCount {
                    self.tableView.insertRows(at: [IndexPath(row: Int(change.newIndex), section: 0)], with: .top)
                }
                
            case .removed:
                self.tableView.deleteRows(at: [IndexPath(row: Int(change.oldIndex), section: 0)], with: .top)
                
            case .modified:
                self.tableView.reloadRows(at: [IndexPath(row: Int(change.newIndex), section: 0)], with: .automatic)
            }
        }
    }

And here is UICollectionView:

 func dataSourceForQuery(_ query: Query) -> FeaturedSessionsCollectionViewDataSource {
        return FeaturedSessionsCollectionViewDataSource(query: query) { (changes, sessions) in
            
            // Dismiss Loader
            self.dismissActivity()
            
            // Perform batch insertion, updating, removal of cells based on changes.
            self.collectionView?.performBatchUpdates({
                changes.forEach { (change) in
                    
                    switch change.type {
                    case .added:
                        
                        // Only insert if needed
                        if let collectionViewItemCount = self.collectionView?.numberOfItems(inSection: 0),
                            collectionViewItemCount < sessions.count {
                            self.collectionView?.insertItems(at: [IndexPath(row: Int(change.newIndex), section: 0)])
                        }
                        
                    case .removed:
                        self.collectionView?.deleteItems(at: [IndexPath(row: Int(change.oldIndex), section: 0)])
                    
                    case .modified:
                        self.collectionView?.reloadItems(at: [IndexPath(row: Int(change.newIndex), section: 0)])
                    }
                }
            }, completion: nil)
        }
    }