value of type AppDelegate has no member managedObjectContext

Question

Code

    let managedObjectContext =
        (UIApplication.sharedApplication.delegate
            as! AppDelegate).managedObjectContext
    

Error:

• Value of type AppDelegate has no member managedObjectContext,

My problem is I want to use managedObjectContext in Xcode 8, but it says AppDelegate have no such member. I want to use this because i want to create a project for ios 9 with core data. I want the definition of managedObjectContext,please comment if you have

Answer 1

Explanation:

• Error is quite clear, it states that AppDelegate doesn't have a property called managedObjectContext. Check AppDelegate and see if a property with the name managedObjectContext exists.

Reference:

It is very important to learn the following before writing code:

• Concepts - https://developer.apple.com/library/content/documentation/DataManagement/Devpedia-CoreData/coreDataOverview.html#//apple_ref/doc/uid/TP40010398-CH28-SW1

• Step by step guide - https://developer.apple.com/library/content/documentation/Cocoa/Conceptual/CoreData/index.html#//apple_ref/doc/uid/TP40001075-CH2-SW1

Answer 2

You need to just create a project with tick mark of "Use Core Data" and it will available in app delegate of you project.image of project creation and selection of use core data tick mark

    lazy var persistentContainer: NSPersistentContainer = {
    /*
     The persistent container for the application. This implementation
     creates and returns a container, having loaded 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.
    */
    let container = NSPersistentContainer(name: "temp")
    container.loadPersistentStores(completionHandler: { (storeDescription, error) in
        if let error = error as NSError? {
            // Replace this implementation with code to handle the error appropriately.
            // fatalError() 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.

            /*
             Typical reasons for an error here include:
             * The parent directory does not exist, cannot be created, or disallows writing.
             * The persistent store is not accessible, due to permissions or data protection when the device is locked.
             * The device is out of space.
             * The store could not be migrated to the current model version.
             Check the error message to determine what the actual problem was.
             */
            fatalError("Unresolved error \(error), \(error.userInfo)")
        }
    })
    return container
}()

Use in app delegate

let context = persistentContainer.viewContext