iOS Core Data: Convert result of fetch request to an array

Question

I'm trying to put the results of a fetch request into an array. My code:

let appDelegate = UIApplication.sharedApplication().delegate as! AppDelegate
    let managedContext = appDelegate.managedObjectContext
    let fetchRequest = NSFetchRequest(entityName: "CLIENTS")
    var mobClients = [NSManagedObject]()
    var arrayAllPhoneNumbers = [String]()

    do {
        let results = try managedContext.executeFetchRequest(fetchRequest)
        mobClients = results as! [NSManagedObject]

        for clientPhoneNumber in mobClients {

            let myClientPhoneNumber = clientPhoneNumber.valueForKey("clientsMobilePhoneNumber") as! String
            print(myClientPhoneNumber)
            //The numbers print out just fine, one below the other
            //
            //Now the results need to go into the array I've declared above ---> arrayAllPhoneNumbers

            messageVC.recipients = arrayAllPhoneNumbers // Optionally add some tel numbers

        }

    } catch
        let error as NSError {
            print("Could not fetch \(error), \(error.userInfo)")
    }

As illustrated, all the phone numbers needs to be captured in an array. How do I accomplish that?

You would be better served creating NSManagedObject sub-classes that represent your core data entities, Additionally, if you only want the phone numbers you should use a predicate in your initial fetch and then you can assign the resulting array of phone numbers directly. — Fred Faust
– Fred Faust, Commented Feb 28, 2016 at 18:20
That's a lot of (overwhelming) info for a n00b like myself! Give me a day or two to google all that, and if you don't mind, I would like to come back to you on this. Thanks for the response in the mean time! — Jaco Griesel
– Jaco Griesel, Commented Feb 28, 2016 at 18:41

paulvs · Accepted Answer · 2016-02-28 18:10:51Z

4

Instead of your for-loop and the code inside it, use this:

arrayAllPhoneNumbers = mobClients.map({ clientPhoneNumber in
    clientPhoneNumber.valueForKey("clientsMobilePhoneNumber") as! String
})
messageVC.recipients = arrayAllPhoneNumbers

answered Feb 28, 2016 at 18:10

paulvs

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1 Comment

Jaco Griesel Over a year ago

Works like a charm! Thank you very much!

Eendje · Accepted Answer · 2016-02-28 18:22:16Z

1

let request = NSFetchRequest(entityName: "CLIENTS")
let results = (try? managedContext.executeFetchRequest(request)) as? [NSManagedObject] ?? []

let numbers = results.flatMap { $0.valueForKey("clientsMobilePhoneNumber" as? String }

numbers is now an array of your phone numbers.

But like thefredelement said, it's better to subclass it so you can just cast it to that subclass and access the phone numbers directly.

answered Feb 28, 2016 at 18:22

Eendje

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Comments

Sébastien REMY · Accepted Answer · 2020-06-29 17:06:22Z

0

Swift 5 : flatMap is deprecated, use compactMap

let request = NSFetchRequest(entityName: "CLIENTS")
let results = (try? managedContext.executeFetchRequest(request)) as? [NSManagedObject] ?? []

let numbers = compactMap { $0.valueForKey("clientsMobilePhoneNumber" as? String }

answered Jun 29, 2020 at 17:06

Sébastien REMY

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