Pleeeease帮助。我正在制作这个应用程序，但我没有在开头添加coreData。我稍后在一些在线教程的帮助下添加了它。一切似乎工作正常，除了我的应用程序在第33行崩溃：
import UIKit
import CoreData
class SittingsViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
//preperation
Stepper.continuous = false
Stepper.autorepeat = false
Stepper.maximumValue = 6
Stepper.minimumValue = 0
valChanged(1)
var request = NSFetchRequest(entityName: "Sittings")
request.returnsObjectsAsFaults = false
Stepper.value = managedContext.executeFetchRequest(request, error: nil) as! Double
managedContext.save(nil)
}
//global vars and iboutlets
@IBOutlet var Stepper: UIStepper!
@IBOutlet var AproximateLabel: UILabel!
var decimalPlaces = Int()
//core data
var appDel = UIApplication.sharedApplication().delegate as! AppDelegate
var managedContext = SittingsViewController().appDel.managedObjectContext! //my error happens here
let entity = NSEntityDescription.entityForName("Sittings",
inManagedObjectContext:
SittingsViewController().managedContext)
let decimal = NSManagedObject(entity: SittingsViewController().entity!,
insertIntoManagedObjectContext:SittingsViewController().managedContext)
@IBAction func stepperValueChanged(sender: UIStepper) {
valChanged(Int(sender.value))
AproximateLabel.text = Int(sender.value).description
}
//segue
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
var firstView: ViewController = segue.destinationViewController as! ViewController
firstView.decimalPlaces = Int(decimalPlaces)
}
func valChanged(num: Int) {
let entity = NSEntityDescription.entityForName("Sittings",
inManagedObjectContext:
managedContext)
let decimal = NSManagedObject(entity: entity!,
insertIntoManagedObjectContext:managedContext)
//3
decimal.setValue(num, forKey: "decimalPlaces")
//4
var error: NSError?
if !managedContext.save(&error) {
println("Could not save \(error), \(error?.userInfo)")
}
decimalPlaces = num
}
}
如果您需要更多代码或其他任何内容，我很乐意为您提供帮助！
回溯：
https://drive.google.com/file/d/0Bxu11l4-PozQTHk5cmYydlZ3Zm8/view?usp=sharing
的AppDelegate：
导入UIKit 导入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.
UIApplication.sharedApplication().statusBarStyle = UIStatusBarStyle.LightContent
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.
}
func applicationWillTerminate(application: UIApplication) {
// Called when the application is about to terminate. Save data if appropriate. See also applicationDidEnterBackground:.
self.saveContext()
}
// 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.math" 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("math", 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("math.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()
}
}
}
}
非常感谢！
我刚发现我的managedObjectContext是零，但我不知道为什么？ 有人可以帮忙吗？