Update "order" column using NSManagedObject

gistfile1.txt

private func _updateOrdersIfPossible(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 nsPlainNote = NSPlainNoteRepository.getNSPlainNote(context: context, objectID: updateOrders[0].objectID, propertiesToFetch: ["order"]) {
            nsPlainNote.order = prevOrder
        }
    }
    
    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 nsPlainNote = NSPlainNoteRepository.getNSPlainNote(context: context, objectID: updateOrder.objectID, propertiesToFetch: ["order"]) {
                nsPlainNote.order = newOrder
            }
        } else {
            // Skip from updating. Fast!
            
            prevOrder = updateOrder.order
        }
    }   // for index in 1..<count

    RepositoryUtils.saveContextIfPossible(context)
}

static func getNSPlainNote(context: NSManagedObjectContext, objectID: NSManagedObjectID, propertiesToFetch: [Any]?) -> NSPlainNote? {
    var nsPlainNote: NSPlainNote? = nil
    
    context.performAndWait {
        let fetchRequest = NSPlainNote.fetchRequest()
        
        fetchRequest.predicate = NSPredicate(format: "self = %@", objectID)
        
        fetchRequest.propertiesToFetch = propertiesToFetch
        
        fetchRequest.fetchLimit = 1
        
        do {
            let nsPlainNotes = try fetchRequest.execute()
            
            if let _nsPlainNote = nsPlainNotes.first {
                nsPlainNote = _nsPlainNote
            }
        } catch {
            error_log(error)
        }
    }

    return nsPlainNote
}