CODEWITHSUNDEEP
iosswiftcore-data
Robert McCoy
Robert McCoy

Reputation: 661

Core Data Context not Saving

I have been struggling to get Core Data working in my mobile application. The values consistently stay nil after all of my attempts to fix it. This is the related information for saving my information, mind you there will only be one result at any point in time.

var appDel:AppDelegate = (UIApplication.sharedApplication().delegate as AppDelegate)
var context:NSManagedObjectContext = appDel.managedObjectContext!
let insertBools = NSEntityDescription.insertNewObjectForEntityForName("Codes", inManagedObjectContext: context) as NSManagedObject

Later in the code after doing a string check comparison based upon the QR Code that is scanned...

else if (metadataObj.stringValue == "oiu2162poiu" && res.qrCode5_Found != true) {
    captureSession?.stopRunning()
    println("\(metadataObj.stringValue) qrCode5_Found if")
    insertBools.setValue(true, forKey: "qrCode5_Found")
    var alert = UIAlertController(title: "Code Found!", message: "You have found and scanned Code #5!", preferredStyle: UIAlertControllerStyle.Alert)
    alert.addAction(UIAlertAction(title: "OK", style: UIAlertActionStyle.Default, handler: nil))
    self.presentViewController(alert, animated: true, completion: nil)
    insertBools.managedObjectContext?.save(nil)
    self.navigationController?.popViewControllerAnimated(false)
}

I'm not sure where I'm going wrong. The View controller before this retrieves the values of each of these keys every time it loads and displays certain labels based upon whether or not some of the elements has been found (This is a scavenger hunt style portion of the application).

override func viewDidLoad() {
    super.viewDidLoad()
    var appDel:AppDelegate = (UIApplication.sharedApplication().delegate as AppDelegate)
    var context:NSManagedObjectContext = appDel.managedObjectContext!
    let request = NSFetchRequest(entityName: "Codes")
    request.returnsObjectsAsFaults = false

    var results:NSArray = context.executeFetchRequest(request, error: nil)!

    if (results.count == 1) {
        var res = results[0] as Codes
        if (res.qrCode1_Found != true) {
            qrCode1.enabled = true
            scanQRCodeButton.enabled = true
            qrLeftList.enabled = true
        }
        if (res.qrCode2_Found != true) {
            qrCode2.enabled = true
            scanQRCodeButton.enabled = true
            qrLeftList.enabled = true
        }
        if (res.qrCode3_Found != true) {
            qrCode3.enabled = true
            scanQRCodeButton.enabled = true
            qrLeftList.enabled = true
        }
        if (res.qrCode4_Found != true) {
            qrCode4.enabled = true
            scanQRCodeButton.enabled = true
            qrLeftList.enabled = true
        }
        if (res.qrCode5_Found != true) {
            qrCode5.enabled = false
            scanQRCodeButton.enabled = true
            qrLeftList.enabled = true
        }
        if (res.qrCode5_Found == true && res.qrCode4_Found == true && res.qrCode3_Found == true && res.qrCode2_Found == true && res.qrCode1_Found == true) {
            registerButton.enabled = true
            scanQRCodeButton.enabled = false
        }
    }
........

And my AppDelegate file, I didn't originally include Core Data but I imported it all manually, and the compiler isn't throwing any errors.

//
//  AppDelegate.swift
//  webview_test
//
//  Created by Robert on 3/19/15.
//  Copyright (c) 2015 Robert. All rights reserved.
//

import UIKit
import CoreData

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

var window: UIWindow?


func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
    // Override point for customization after application launch.
    return true
}

func applicationWillResignActive(application: UIApplication) {
    // Sent when the application is about to move from active to inactive state. This can occur for certain types of temporary interruptions (such as an incoming phone call or SMS message) or when the user quits the application and it begins the transition to the background state.
    // Use this method to pause ongoing tasks, disable timers, and throttle down OpenGL ES frame rates. Games should use this method to pause the game.
}

func applicationDidEnterBackground(application: UIApplication) {
    // Use this method to release shared resources, save user data, invalidate timers, and store enough application state information to restore your application to its current state in case it is terminated later.
    // If your application supports background execution, this method is called instead of applicationWillTerminate: when the user quits.
}

func applicationWillEnterForeground(application: UIApplication) {
    // Called as part of the transition from the background to the inactive state; here you can undo many of the changes made on entering the background.
}

func applicationDidBecomeActive(application: UIApplication) {
    // Restart any tasks that were paused (or not yet started) while the application was inactive. If the application was previously in the background, optionally refresh the user interface.
}
// MARK: - Core Data stack

lazy var applicationDocumentsDirectory: NSURL = {
    // The directory the application uses to store the Core Data store file. This code uses a directory named "com.xxxx.ProjectName" in the application's documents Application Support directory.
    let urls = NSFileManager.defaultManager().URLsForDirectory(.DocumentDirectory, inDomains: .UserDomainMask)
    return urls[urls.count-1] as NSURL
    }()

lazy var managedObjectModel: NSManagedObjectModel = {
    // The managed object model for the application. This property is not optional. It is a fatal error for the application not to be able to find and load its model.
    let modelURL = NSBundle.mainBundle().URLForResource("SavedVariables", withExtension: "momd")!
    return NSManagedObjectModel(contentsOfURL: modelURL)!
    }()

lazy var persistentStoreCoordinator: NSPersistentStoreCoordinator? = {
    // The persistent store coordinator for the application. This implementation creates and return a coordinator, having added the store for the application to it. This property is optional since there are legitimate error conditions that could cause the creation of the store to fail.
    // Create the coordinator and store
    var coordinator: NSPersistentStoreCoordinator? = NSPersistentStoreCoordinator(managedObjectModel: self.managedObjectModel)
    let url = self.applicationDocumentsDirectory.URLByAppendingPathComponent("webview_test.sqlite")
    var error: NSError? = nil
    var failureReason = "There was an error creating or loading the application's saved data."
    if coordinator!.addPersistentStoreWithType(NSSQLiteStoreType, configuration: nil, URL: url, options: nil, error: &error) == nil {
        coordinator = nil
        // Report any error we got.
        var dict = [String: AnyObject]()
        dict[NSLocalizedDescriptionKey] = "Failed to initialize the application's saved data"
        dict[NSLocalizedFailureReasonErrorKey] = failureReason
        dict[NSUnderlyingErrorKey] = error
        error = NSError(domain: "YOUR_ERROR_DOMAIN", code: 9999, userInfo: dict)
        // Replace this with code to handle the error appropriately.
        // abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
        NSLog("Unresolved error \(error), \(error!.userInfo)")
        abort()
    }

    return coordinator
    }()

lazy var managedObjectContext: NSManagedObjectContext? = {
    // Returns the managed object context for the application (which is already bound to the persistent store coordinator for the application.) This property is optional since there are legitimate error conditions that could cause the creation of the context to fail.
    let coordinator = self.persistentStoreCoordinator
    if coordinator == nil {
        return nil
    }
    var managedObjectContext = NSManagedObjectContext()
    managedObjectContext.persistentStoreCoordinator = coordinator
    return managedObjectContext
    }()

// MARK: - Core Data Saving support

func saveContext () {
    if let moc = self.managedObjectContext {
        var error: NSError? = nil
        if moc.hasChanges && !moc.save(&error) {
            // Replace this implementation with code to handle the error appropriately.
            // abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
            NSLog("Unresolved error \(error), \(error!.userInfo)")
            abort()
        }
    }
}

func applicationWillTerminate(application: UIApplication) {
    // Called when the application is about to terminate. Save data if appropriate. See also applicationDidEnterBackground:.
    // Saves changes in the application's managed object context before the application terminates.
    self.saveContext()
}

}

And as a sidenote...if someone could tell me how to force the program to wait for a user to press the OK button on an alert before continuing I would forever be in your debt.

Upvotes: 1

Views: 1315

Answers (1)

Robert McCoy
Robert McCoy

Reputation: 661

I misunderstood the concept of Core Data. Instead I now loop through each result instead of

var res = results[0] as Codes

with 

for res in results as [NSManagedObject] {
    ....
}

and get the results I need and then use those for comparison, it's a shoddy work around, but it works.

Upvotes: 1

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