Swift Tutorial - Core Data - Notes

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Swift Tutorial - Core Data

From Swift Tutorial - Core Data by rm2kdev

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Add some comments into the project.

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//
//  ViewController.swift
//  test Core Data
//
//  Created by Will Ge on 8/21/15.
//  Copyright (c) 2015 gewill.org. All rights reserved.
//

import UIKit
import CoreData

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }


    @IBOutlet weak var textUserName: UITextField!
    @IBOutlet weak var textPassword: UITextField!
    
    @IBAction func saveButton(sender: AnyObject) {
        
        // Cora Data already settled done in AppDelegate.swift
        // get the ManagedObjectContext
        var appDel = UIApplication .sharedApplication().delegate as! AppDelegate
        var context: NSManagedObjectContext = appDel.managedObjectContext!
        
        // get the ManagedObject
        var newUser = NSEntityDescription.insertNewObjectForEntityForName("Users", inManagedObjectContext: context) as! NSManagedObject
        
        // set value for key
        newUser.setValue("" + textUserName.text, forKey: "username")
        newUser.setValue("" + textPassword.text, forKey: "password")
        
        // save
        context.save(nil)
        print("New username: \(textPassword.text) and password: \(textPassword.text) saved successfully.\n")
        
        
    }
  
    @IBAction func loadButton(sender: AnyObject) {
        
        var appDel = UIApplication .sharedApplication().delegate as! AppDelegate
        var context: NSManagedObjectContext = appDel.managedObjectContext!
        
        // add FetchRequest and add Predicate/ SortDescriptor etc.
        var request = NSFetchRequest(entityName: "Users")
        request.returnsObjectsAsFaults = false
        request.predicate = NSPredicate(format: "username = %@", "" + textUserName.text)
        
        var requests: NSArray = context.executeFetchRequest(request, error: nil)!
        
        if (requests.count > 0) {
            
            var res = requests[0] as! NSManagedObject
            textUserName.text = res.valueForKeyPath("username") as! String
            textPassword.text = res.valueForKeyPath("password") as! String
            
        } else {
            
            print("0 Results Returned... Poterial Error.\n")
        }
        
    }
}

test_Core_Data.xcdatamodeld settings

Discovry - Core Data stack

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//  AppDelegate.swift


    // 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 "org.gewill.test_Core_Data" 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("test_Core_Data", 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("test_Core_Data.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()
            }
        }
    }

}

Debug:

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p applicationDocumentsDirectory
(NSURL) $R0 = 0x00000001740a8b20 "file:///var/mobile/Containers/Data/Application/601088B9-EB64-4E8D-9817-96E23D0D5D7E/Documents/"
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ssh root@192.168.0.101
root# cd /var/mobile/Containers/Data/Application/601088B9-EB64-4E8D-9817-96E23D0D5D7E/Documents/
root# ls -la
total 192
drwxr-xr-x 2 mobile mobile    170 Aug 21 22:16 ./
drwxr-xr-x 5 mobile mobile    204 Aug 21 22:16 ../
-rw-r--r-- 1 mobile mobile  20480 Aug 21 22:16 test_Core_Data.sqlite
-rw-r--r-- 1 mobile mobile  32768 Aug 21 22:24 test_Core_Data.sqlite-shm
-rw-r--r-- 1 mobile mobile 140112 Aug 21 22:24 test_Core_Data.sqlite-wal

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