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.
Related
I have 3 build configurations, Debug, Release and Development. For Development I have created a new Scheme with a new bundleID, Product name etc so I can see which one is DEV and DEBUG on my phone.
I am using Core Data and for the DEBUG with the original bundleID everything works fine, but when I switch to use the Development one, I get an error when I try to create a new entity with name:
NSEntityDescription.insertNewObject(forEntityName: "MyEntity", into: managedContext)
The error I get:
Could not cast value of type 'NSManagedObject_MyEntity_' (0x600002d62b20) to 'AppName_DEV.MyEntity' (0x102bf9368).
It seems like it is trying to get the MyEntity class from my "AppName DEV" scheme not the "AppName". I can't find any Build Settings where I could point it to use the same model?
Any ideas on how to use core data with multiple build configurations?
Ok, I found the problem. Since I was trying to revive a very old app originally written in swift 2, it occurred to me that I might double check how was the data model created. After hours of tinkering with the core data set up process, I changed 2 things that finally get it to work.
1.) In the .xcdatamodeld file, on the right side in the Data Model Inspector, make sure that you have the Module field EMPTY I had my AppName Inside, which was the same as the original target name.
2.) I added #objc(EntityName) to the NSManagedObject subclass I had.
Of course I cleaned the project, deleted the app from the simulator and installed it again.
If you have an issue like that, hope that whis will help you, good luck!
I have a project and I am using core data.
I have some entities, with attributes. When I started the project I choose some atributes and now I want to change their types (Int to String for example). ANd so I did it.
THe thing is, I am getting errors...
I checked the code, I think every thing is ok.
I even deleted the entire entity and made a new one with some name but it doesn't work.
How can I change it with success?
You can use code data migration for this by creating new version..
To change data types you need to create a new version of the database, you can not just simply modifie it because that way your users would have to delete and redownload your app every time you change something.
Here you can read how to do this.
The simulator or device you are running the app on still 'remembers' the old type and data. Simply hold down on the app and press the 'X' to delete it. When you press play in XCode it will reinstall the app with the new data types.
I have been trying very unsuccessfully to create a simple UIManagedDocument library style application (separate documents saved to iCloud).
I am confused with the following:
Do I subclass UIManagedDocument and set up the persistentStoreCoordinator, ManagedObjectModel & ManagedObjectContext within this subclass, or are these supposed to be configured within the AppDelegate (and if so, how do I go about refreshing the persistentStoreCoordinator to look at the new file - it seems that once that has read a persistentStore that I can't get it to read a new persistent store)?
Richard's example is an excellent example. I used it and the PragmaProg book on core data http://pragprog.com/book/mzcd2/core-data as a guide for creating my managed document module on github.
See: https://github.com/dtrotzjr/APManagedDocument
My code makes use of iOS 7 iCloud Core Data behavior which I cannot comment on publicly until the NDA is lifted. Feel free to ping me directly if you have any questions.
I've just posted a project based on Rick Warren's example: MultiDocumentPlusUUID. In his "Syncing Multiple Core Data Documents Using iCloud" post, Rick writes:
Another bug often shows up when I start trying to pass changes back and forth between devices that both have the same file open. The first sync always seems to work--and it seems to work pretty well as long as each subsequent sync is in the same direction.
MultiDocumentPlusUUID compiles and runs on iOS 7.1b4, and can ping-pong updates to a given document successfully.
Can I use "Automatic Lightweight Migration" if my already release v1 didn't have a versioned Core Data model?
If yes, are there any key changed to the documented steps I need to apply?
Not only can you do this, in one sense it is the only way you can do this. From the Apple Documentation, "To create a versioned model, you start with a normal model..."
Your v1 had a normal model. As long as you have that model, and you follow the steps linked in that tutorial to create a versioned model, lightweight migration will work—if your migration meets the usual lightweight migration requirements. The lightweight migration happens in your v2 app (or in v1.1 or whatever). The data model that was in your v1 app essentially has no relevance. What Core Data needs is to find that the new v2 app has a copy of the data model that matches what is found in the Core Data store on the local device, and has a new data model that describes how you want the data to be stored from this point forward. If the changes required meet the requirements for lightweight migration, it then does it.
What are those requirements? From the Apple documentation on Lightweight Migration:
To perform a lightweight migration, Core Data needs to be able to find
the source and destination managed object models itself at runtime.
(Core Data searches the bundles returned by NSBundle’s allBundles and
allFrameworks methods.) It must then analyze the schema changes to
persistent entities and properties and generate an inferred mapping
model. For Core Data to be able to do this, the changes must fit an
obvious migration pattern, for example:
• Simple addition of a new attribute
• A non-optional attribute becoming optional
• An optional attribute becoming non-optional, and defining a
default value.
If you rename an entity or property, you can set the
renaming identifier in the destination model to the name of the
corresponding property or entity in the source model. You typically
set the renaming identifier using the Xcode Data Modeling tool, (for
either an NSEntityDescription or an NSPropertyDescription object). In
Xcode, the renaming identifier is in the User Info pane of the Detail
Pane, below the version hash modifier (see The Browser View in Xcode
Tools for Core Data). You can also set the identifier at runtime using
setRenamingIdentifier:. For example, to handle
• Renaming of an entity Car to Automobile,
• and Renaming the Car’s color
attribute to paintColor
you would include the following code after
loading the destination data model, and before attempting to open a
store file:
NSEntityDescription *automobile = [[destinationModel entitiesByName] objectForKey:#"Automobile"];
[automobile setRenamingIdentifier:#"Car"];
NSPropertyDescription *paintColor = [[automobile attributesByName] objectForKey:#"paintColor"];
[paintColor setRenamingIdentifier:#"color"];
In summary, you didn't miss the boat, and it's not too late to make use of these features of Core Data. :) And to answer your specific question, there is nothing you need to change from the standard steps outlined in the documentation.
Later update
Further thoughts based on your comment to another answer, where you said:
so just to confirm, I don't have to in XCode back track my core data
model to what it looked like a v1 and then version it then? So I can
just create the first core data model version at the point where my
application is at v2?
From what you are saying here, the issue would appear to be different to the initial question. Your initial question says that you have already released v1 of your app, without explicitly adding a versioned model. However, this statement implies that you have made changes to your core data model for v2 of your app, without first creating a versioned data model. This is quite a different thing.
If this is the case, then your job is more difficult. However, you can retrieve what you need presuming you keep backups of your source code or manage your code in a repository like git (and I would recommend all developers do both). If you've already changed your core data model for v2, what you need to do is turn the current data model into a versioned model, then restore/checkout a copy of v1 of your app, copy the core data model (the *.xcdatamodel file) from there into your current project, so that you then have both the v1 data model and your newer one. Then you will potentially be able to use lightweight migration, as discussed above.
Note that the key issue here is when you changed your data model. Whether your app is called v1 or v2 is essentially irrelevant to the question, other than obviously that it may be that you introduced changes to the data model at the same time you changed the version number to v2 of the app.
Save off your current non-versioned model file (the .xcdatamodel package).
Now, create a new model version. You will have instead of a single .xcdatamodel package, a .xcdatamodeld file. Right click on it in Finder, select "show package contents". That opens it as a directory - drag your old .xcdatamodel file into that directory alongside the new versioned .xcdatamodel package.
Now an automatic migration should work if it's possible, you may not need a mapping model. Test to be sure though!!!
I have used this approach in a production application and it did work. As long as CoreData can find both the current model the app is using, and the model the new version of the model the application relies on it can attempt the automatic migration.
yes it is possible because by creating the new version you can also create a version mapping file. This file tells the application which keys will be changed to which keys in the new version (and of course which one are deleted and created)
the apple documentation: http://developer.apple.com/library/ios/#documentation/Cocoa/Conceptual/CoreDataVersioning/Articles/vmMappingOverview.html
I have a simple problem, I have an app based on CoreData and I need to change the structure a little. How can I migrate the old structure into the new one. Just adding one attribute will chrash the whole app.
Thanks
Have a look at the Apple Docs
http://developer.apple.com/iPhone/library/documentation/Cocoa/Conceptual/CoreDataVersioning/Introduction/Introduction.html
Once you have the basics of Core Data down, you can implement versioning. Until then, if you're just testing things out, you can always delete the app from the Simulator or device. Reinstalling the app will create a fresh data store (usually).
When you finally do get to the point where you want to version, you add a new one by clicking on your core data model file (YourApp.xcdatamodel). Then pull down the 'Design' menu, hover on 'Data Model', and click 'Add Model Version'.
Don't forget to change your model extension from 'mom' to 'momd' (wherever you're loading it, probably in your app delegate), and when you have your new version in hand, go back to that menu and click 'Set Current Version'.