Populate Array with One Core Data Attribute

Question

I am having some trouble putting entries from one attribute into an Array. This Array will then be used in a UIPickerview. Language is Swift.

There are many tutorials on Pickerviews in swift and Core Data in swift. But I haven't found one that explains how to fill an array with just one of the attributes.

To make matters worse I am still pretty bad at converting objective c into swift.

So I have two questions:

1 is my solution correct to build an array from one attribute and then fill the Pickerview with the content from that array?

2 how do you get that array in swift?

objective c code on core data => array

---

Objective C from link:

NSManagedObjectContext *managedObjectContext = [self managedObjectContext];
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc]
                                initWithEntityName:@"WeightLog"];
self.contactarray = [[managedObjectContext executeFetchRequest:fetchRequest
                                                         error:nil] mutableCopy];

titleNames = [[NSMutableArray alloc] init];
for (int i =0; i<=self.contactarray.count; i++) {
    NSManagedObject *device = [self.contactarray objectAtIndex:i];
    [titleNames addObject:device];
}

---

The part I can't write in Swift:

NSManagedObjectContext *managedObjectContext = [self managedObjectContext];
        NSFetchRequest *fetchRequest = [[NSFetchRequest alloc]
            initWithEntityName:@"WeightLog"];
        self.contactarray = [[managedObjectContext executeFetchRequest:fetchRequest
        error:nil] mutableCopy];

Thank you!

---

Edit: Working code!

var myTitle: String = ""


var appDel:AppDelegate = (UIApplication.sharedApplication().delegate as AppDelegate)
        var context:NSManagedObjectContext = appDel.managedObjectContext!

        let fetchRequest = NSFetchRequest(entityName:"MyEntity")
        var myTitles: [String] = []
        if let myLogs = context.executeFetchRequest(fetchRequest, error: nil) {
            myTitles = myLogs.map { $0.myTitle } // get an array of the 'myTitle' attributes
            println(myTitles)

Answer 1

I'm just typing this in here, so not sure if it even compiles:

let moc = self.managedObjectContext()
let fetchRequest = NSFetchRequest(entityName:"WeightLog")
var titleNames: [String] = []
if let weightLogs = moc.executeFetchRequest(fetchRequest, error: nil) as? [WeightLog] {
  titleNames = weightLogs.map { $0.title } // get an array of the 'title' attributes
}

If you're returning the titleNames array from a method then I'd write it like this, ie not use a var titleNames :

let moc = self.managedObjectContext()
let fetchRequest = NSFetchRequest(entityName:"WeightLog")
if let weightLogs = moc.executeFetchRequest(fetchRequest, error: nil) as? [WeightLog] {
  return weightLogs.map { $0.title } // get an array of the 'title' attributes
} else {
  return []
}

Answer 2

lazy  var managedObjectContext : NSManagedObjectContext? = {   
    let appDelegate  = UIApplication.sharedApplication().delegate as AppDelegate

    if let managedObjectContext  = appDelegate.managedObjectContext 
    {
        return managedObjectContext
    }
    else 
    {
        return nil
    }
}()

let fetchRequest = NSFetchRequest(entityName: "Entity")

if let fetchResults = managedObjectContext!.executeFetchRequest(fetchRequest, error: nil) as? [Entity] 
{

    for info in fetchResults
    {
        println(info.valueForKey("keyname"));
    }
}