I am just learning Core Data on iPhone and the tutorial I am following says to create a new file and select NSManagedObject as the template. However, in Xcode 3.2.2 it seems to be gone. Is there any way to get it back or some kind of workaround?
Thanks in advance!
Select the entity in your Core Data model (xcdatamodel) file first, and then create a new file. The managed object template should show up.
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So I am pretty new to CoreData in Xcode and I have been looking for tutorials to see how to get more familiar with it and start working with it. A tutorial I have been watching, mentions that we need to Generate code for an entity that I created. I select Editor -> Create NSManagedObject Subclass to generate the code for the entity. But the files generated come full of errors and warnings that I haven't caused. I will attach screenshots for some more details.
That's the entity that I am creating in CoreData
That's the first generated file for the entity
That's the second file generated for the entity
The below are the errors and warnings I am getting:
File 'Person+CoreDataClass.swift' is part of module 'CoreData'; ignoring import
File 'Person+CoreDataProperties.swift' is part of module 'CoreData'; ignoring import
Only classes that inherit from NSObject can be declared #objc
Cannot find type 'NSManagedObject' in scope
Cannot find type 'NSFetchRequest' in scope
Note that I have enabled CoreData when I first created the project and I haven't made any changes to any other files in the project.
I would appreciate any kind of help since I haven't got any experience yet with CoreData. Thank you!
Try creating a new project with a different name (not CoreData)
I just declared an entity called "Users" array:
var UsersArray = [Users]()
I got this error:
use of unresolved identifiers "Users"
hint : I did import CoreData and created the entity
Please try this solutions !!
Solution 1 :-
Product->Build for testing solved this issue for me(it solves most unresolved identifier bugs for some strange reason)
Solution 2 :-
changing import Foundation to import UIKit.
It seems like UIApplication isn't included in Foundation framework.
Solution 3 :- Highlight the Data Model, go to Editor -> Create NSManagedObject Subclass...
Solution 4 :-
Create the NSManagedObject files and then delete them and everything is fixed.
Hope this helps thank you.
If your entity is actually created, just close and re-open XCode. This works for me everytime. The other solutions, such as clean build, build etc, didn't work for me.
Just ran into this issue after renaming an entity and figured I should post here how I resolved it.
Typically after making changes in the data model and getting compilation errors, I just do Product > Clean Build Folder, then Product > Build and that should take care of the errors.
However, the steps above didn't help this time. After scratching my head for while, I found the culprit with following steps:
In the Project navigator, select your .xcdatamodelId file
In the Configurations section, select the appropriate configuration
Look for the entity in question and make sure the class name is correct (in my case, the entity and the class were not the same)
Other possible solutions:
(A) Re-launch Xcode
This is the solution that worked for me. (See this answer)
(B) Check if you did not forget to finalize your entity description
Typically: forgot to assign a type to one of the attributes (still "undefined").
(C) Clear derived data
Reason: The generated core data managed objects subclasses's source code files are in the project’s derived data location.
Note: you might have to re-link your swift packages is using SPM.
I also had to deal with this issue even working with the latest Xcode12.3 on a SwiftUI project where I didn't checked the CoreData option at project creation.
After adding a class to instantiate the NSPersistentContainer, loading the stores, creating model.xcdatamodel file with an entity and a text field plus a button on a view, then it shows an error saying: "cannot find Item in scope".
It's a bit difficult to write code when you expect the entity to help out with autocomplete. First, I thought I forgot to initialize my class or missed a bracket, but it wasn't that either.
I tried cleaning up, rebuilding and running the project several times with build failed as result. I had to close this particular project then all errors got dismissed. No needed to restart Xcode.
I faced the same issue. Doesn't included Coredata on the beginning of the project. Later added necessary files and core data stack. But when trying to fetch the data from the Entity name and the Xcode throwing the same error.
Later, I closed the project and again opened on Xcode and it started to work.
I had this issue with an .xcdatamodel that I had created in another project and moved it into this one.
I solved it by selecting the .xcdatamodel file, turned of the "File Inspector" and then under "Target Membership", I made sure that all the targets were selected.
for me the entity name and class name was different, and I was refering to entity name for Data Type
I am creating an application using Core Data. But When I run my app it crashes. It shows me this reason:
reason = "The model used to open the store is incompatible with the one used to create the store";
What should I do now?
I think you need to refer this link and refer to answer given by Grouchal in the link below:
What do I have to do to get Core Data to automatically migrate models?
If you need any further help please do let me know.
Hope this helps you.
It means that you created a model, run the app, modified the model (by adding or removing managed objects, renaming object properties and so on...) and reopened the app without migrating the data first. I still have to try this by myself but, you should definitely take a look here: http://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/CoreDataVersioning/Introduction/Introduction.html
You can just delete the app (icon) from the simulator or device. Then, rebuild and run.
As dave explained, you have modified the core data structure (the store). If you're using the standard template, in the new rebuild a new model (NSManagedObjectModel) will be created that is compatible with your newly modified store.
You will probably be making many changes to the core data structure (adding or deleting an entity or some property or relationship), and, each time you do, you can just delete the app from the simulator or device.
I've been working with core data (successfully ;) , following some tutorials and kind of getting all, but now I have a question about some basic tutorial I found some time ago (the author is not responding so here we go!)
this is the tutorial, and the code for it is here
in this tutorial, there are 2 xcdatamodels??, why? what is the timeStamp on the Event does?? I checked it in sqlitemanager, and after creating some data, timestamp doesnt save anything,
so was it a mistake to leave the Event entity? with its datamodel?
or is there something Im missing?
thank you!
It looks like CoreDataTutorialPart1.xcdatamodel (the model file containing the Event entity) was auto-generated by the Core Data Xcode template and isn't actually used anywhere in the project.
I am trying to generate classes for my .xcdatamodel entities, but am not given the Manage Object Class option when I click on an entity and select File>New File. I've looked under both the iPhone and Mac OS X catagories, but it is not listed anywhere.
Here are the steps I am taking,
I create a new project being sure to check the "Use Core Data" checkbox. Once the project is created, I open .xcdatamodel, create an entity, and add a few attributes. Next, I click on the entity and choose File>New File, but all I see are only Objective-C, Objective-c test case class, and UIVewController subclass.
Am I missing a step?
Thanks in advance
Take a look at the Core Data Tutorial for iPhone OS and look at this section: Custom Managed Object Subclass. If you still aren't seeing the Core Data related items for the iPhone OS check the version of the SDK you are targeting. I believe Core Data has only been available since SDK 3.
Had the same problem. Restarting x-code helped me.