Using Long Press Reorder for swift reorder realm objects ID after dragging

RealmReorderIDAfterTableDrag.swift

extension CategoryViewController {
    
    override func positionChanged(currentIndex: IndexPath, newIndex: IndexPath) {
        // currentIndex and newIndex rows are swapped, implement accordingly
    }
    
    override func reorderFinished(initialIndex: IndexPath, finalIndex: IndexPath) {
        // Gesture is finished and cell is back inside the table at finalIndex position
        try! realm.write {
            guard let sourceObject = categories?[initialIndex.row] else {fatalError()}
            guard let destinationObject = categories?[finalIndex.row] else {fatalError()}
            
            let destinationObjectOrder = destinationObject.id
            
            if initialIndex.row < finalIndex.row {
                
                for index in initialIndex.row...finalIndex.row {
                    let object = categories![index]
                    object.id -= 1
                }
            } else {
                
                for index in (finalIndex.row..<initialIndex.row).reversed() {
                    let object = categories![index]
                    object.id += 1
                }
            }
            sourceObject.id = destinationObjectOrder
            tableView.reloadData()
        }
    }
}