Update "order" column using Batch Update Operation

gistfile1.txt

private func _updateOrdersIfPossible2(context: NSManagedObjectContext, updateOrders: [UpdateOrder]) {
    let count = updateOrders.count
    
    if count < 2 {
        return
    }
    
    var prevOrder = updateOrders[0].order
    
    var updatedObjectIDs = [NSManagedObjectID]()
    
    if !Utils.isValidOrder(prevOrder) {
        prevOrder = prevOrder - 1
        
        precondition(Utils.isValidOrder(prevOrder))
        
        // Time-consuming operation.
        if let updatedObjectID = _updateWithoutMerge(context: context, objectID: updateOrders[0].objectID, propertiesToUpdate: [
            "order": prevOrder
        ]) {
            updatedObjectIDs.append(updatedObjectID)
        }
    }
    
    for index in 1..<count {
        precondition(Utils.isValidOrder(prevOrder))
        
        let updateOrder = updateOrders[index]
        
        if !Utils.isValidOrder(updateOrder.order) || updateOrder.order <= prevOrder {
            var newOrder = prevOrder + 1
            
            if !Utils.isValidOrder(newOrder) {
                newOrder = newOrder + 1
            }
            
            precondition(newOrder > prevOrder)
            
            prevOrder = newOrder
            
            precondition(Utils.isValidOrder(newOrder))
            
            // Time-consuming operation.
            if let updatedObjectID = _updateWithoutMerge(context: context, objectID: updateOrder.objectID, propertiesToUpdate: [
                "order": newOrder
            ]) {
                updatedObjectIDs.append(updatedObjectID)
            }
        } else {
            // Skip from updating. Fast!
            
            prevOrder = updateOrder.order
        }
    }   // for index in 1..<count
    
    if !updatedObjectIDs.isEmpty {
        let changes = [NSUpdatedObjectsKey : updatedObjectIDs]
        CoreDataStack.INSTANCE.mergeChanges(changes)
    }
}

private func _updateWithoutMerge(context: NSManagedObjectContext, objectID: NSManagedObjectID, propertiesToUpdate: [AnyHashable : Any]) -> NSManagedObjectID? {
    return RepositoryUtils._updateWithoutMerge(
        context: context,
        entityName: "NSPlainNote",
        objectID: objectID,
        propertiesToUpdate: propertiesToUpdate
    )
}

static func _updateWithoutMerge(context: NSManagedObjectContext, entityName: String, objectID: NSManagedObjectID, propertiesToUpdate: [AnyHashable : Any]) -> NSManagedObjectID? {
    var result: NSManagedObjectID? = nil
    
    do {
        let batchUpdateRequest = NSBatchUpdateRequest(entityName: entityName)
        batchUpdateRequest.predicate = NSPredicate(format: "self = %@", objectID)
        batchUpdateRequest.propertiesToUpdate = propertiesToUpdate
        batchUpdateRequest.resultType = .updatedObjectIDsResultType
        
        let batchUpdateResult = try context.execute(batchUpdateRequest) as? NSBatchUpdateResult
        
        if let managedObjectIDs = batchUpdateResult?.result as? [NSManagedObjectID] {
            result = managedObjectIDs.first
        }
    } catch {
        context.rollback()
        
        error_log(error)
    }
    
    return result
}