Localization using Core Data - swift

Question

today I read and created around 10 projects related to Core Data. I and finally accomplished what I need but I'm not sure that this approach is very good
I want to change the book title base on the user device lang, I will use
let locale = NSLocale.preferredLanguages()[0] as! String
but first to test the Core Data implementation
Core Data Setup
Source Code
// Get the data from Core Data and change the book title base on the lang
func printBooks(){
let request = NSFetchRequest(entityName: "Langs")
let predicate: NSPredicate = NSPredicate(format: "lang==%#", "fr");
request.returnsObjectsAsFaults = false;
request.predicate = predicate;
let result:NSArray = context.executeFetchRequest(request, error: nil)!;
var frTitle: String!
if(result.count > 0){
for res in result {
let resTmp = res as! NSManagedObject
frTitle = resTmp.valueForKey("langTitle") as! String
}
} else {
println("empty");
}
let requestTwo = NSFetchRequest(entityName: "Book")
requestTwo.returnsObjectsAsFaults = false;
let resultTwo:NSArray = context.executeFetchRequest(requestTwo, error: nil)!;
if(resultTwo.count > 0){
for res in resultTwo {
let resTmpTwo = res as! NSManagedObject
// rename the title
resTmpTwo.setValue(frTitle, forKey: "title");
}
// add to NSArray
entriesArray = resultTwo;
} else {
println("empty two");
}
}
// Adds the new book with the fr version
func insertBook(){
let appDel:AppDelegate = (UIApplication.sharedApplication().delegate as! AppDelegate)
let context: NSManagedObjectContext = appDel.managedObjectContext!
let newBook = NSEntityDescription.insertNewObjectForEntityForName("Book", inManagedObjectContext: context) as! DB.Book
newBook.setValue("Sir Arthur Conan Doyle", forKey: "author")
newBook.setValue("Sherlock Holmes", forKey: "title")
let newLang = NSEntityDescription.insertNewObjectForEntityForName("Langs", inManagedObjectContext: context) as! DB.Langs
newLang.setValue("fr", forKey: "lang")
newLang.setValue("Sherlock Holmes fr - test", forKey: "langTitle")
newBook.setValue(newLang, forKey: "lanBook")
context.save(nil)
println("Saved");
}
override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return self.entriesArray.count
}
override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = self.tableView.dequeueReusableCellWithIdentifier("cell_one", forIndexPath: indexPath) as! UITableViewCell
let db = entriesArray[indexPath.row] as! NSManagedObject
// result in the UITableView is: Sherlock Holmes fr - test
cell.textLabel?.text = db.valueForKey("title") as? String
return cell
}
The code does change the book title, but it can be done much better. I'm not sure how this will be done with large numbers of books.
Anyone who knows how it must be done, pleace be so kind to take a moment of your time and answer with some code :)
Also excuse my bad english..

Answer 1

You should think of implementing a transient property say 'langSpecificTitle' on your NSObjectModel, that would compute this for you from your actual'title' property. Ideally to access localised title, you should access this property and it should get a language specific title by reading the actual 'title' property.
This tutorial explains 'transient' properties well.
Also see this from Apple documentation
Hope this helps.