Using Core Data in Swift 2

Question

Just building a small weather app. In the app i have the user setting the location they want in a text field. I'm trying to use core data to save and fetch this information(not sure if core data is the best way to go) Here is my code to save the data

@IBAction func SetLocation() {
        let appDel: AppDelegate = (UIApplication.sharedApplication().delegate as! AppDelegate)
        let context: NSManagedObjectContext = appDel.managedObjectContext

        let setLocation = NSEntityDescription.insertNewObjectForEntityForName("Location", inManagedObjectContext: context)
        setLocation.setValue("New York, New York", forKey: "setLocation")

        do {
        try context.save()
        print(setLocation)

        } catch {
         print("Could not save location")
        }

        performSegueWithIdentifier("setLocation", sender: nil)


    }

I'm not getting any print statement at all when i click the setLocation button, So i'm not sure what is happening.

In my second view controller i'm trying to fetch the data with this function in viewdidload()

func fetchLocation() {
        let appDel: AppDelegate = (UIApplication.sharedApplication().delegate as! AppDelegate)
        let context: NSManagedObjectContext = appDel.managedObjectContext

        var request = NSFetchRequest(entityName: location)

        do {
            let results =
                try context.executeFetchRequest(request)

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

But i'm stuck on where to go from here to load the result into my buttons label.

Thanks for any help.

Answer 1 · 2016-08-22T17:48:30Z

August 22, 2016 5:48pm

Results is an array of NSManagedObjects. So with the following code you could iterate over the results and get the items and attributes out of it:

 do {
            let results =
                try context.executeFetchRequest(request) as! [NSManagedObject]
            for result in results {
                print (result.valueForKey("setLocation"))
            }


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

But overall i think CoreData is, for something that you want to achieve, a bit of an overkill. You could for example just store the location of the user on disk or in the NSUserDefault settings, if it's a string:

let defaults = NSUserDefaults.standardUserDefaults()
defaults.setObjectForKey("UserLocation")
defaults.synchronize()

You can retrieve the information via:

defaults.objectForKey("UserLocation")

Answer 2 · 2016-08-21T17:58:37Z

August 21, 2016 5:58pm

Have you created an entity in your .xcdatamodeld file called Location and added an attribute setLocation of type String? Then Editor > Create NSManagedObject subclass? In the assignment of the request variable of your fetchLocation method you should replace location with a string "Location". If you print your results you should see something in your debugger. Or try to open your sql file in sqlitebrowser for example (third party program).

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matt taylor

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Using Core Data in Swift 2

2 Answers

Jeroen de Vrind

Jeroen de Vrind

Jeroen de Vrind

Jeroen de Vrind

matt taylor

matt taylor