i have submitted an app on the app store that uses core data.
The problem is that i duplicated my project and then lost the first source code. If i update the app using the "duplicated" source code does it delete all core datas users may have stored? i know that if you change the file file-xcdatamodel without mapping the previous datas you will lose all you had stored, can i assume the duplicated project use the exact same file?
thanks in advance
In that case I think that, if you didn't modify your xcdatamodel, the data stored by user will keep during the upgrade. In order to be sure, you can install your own apo from App Store, save some data, update this app from Xcode with your new version and check if the stored data still are there.
If you've modify your xcdatamodel, you must perform a light or a heavy migration, depending on your canges.
Related
I have some general questions about iphone app updates that involves sqlite db.
With the new update does the existing sqlite db get overwritten with a copy of the new one?
If the update doesn't involve any schema changes then the user should be able to reuse the existing database with their saved data, right? (if the existing database doesn't get overwritten from 1 above )
If there are some schema changes, what's the best way to transfer data from the old database into the new one? Can some one please give me guidelines and sample code?
Only files inside the app bundle are replaced. If the database file is in your app's Documents directory, it will not be replaced. (Note that if you change files inside your app bundle, the code signature will no longer be valid, and the app will not launch. So unless you are using a read-only database, it would have to be in the Documents directory.)
Yes.
What's best depends on the data. You're not going to find sample code for such a generic question. First, you need to detect that your app is running with an old DB version. Then you need to upgrade it.
To check versions:
You could use a different file name for the new schema. If Version2.db does not exist but Version1.db does, do an upgrade.
You could embed a schema version in your database. I have a table called metadata with a name and value column. I use that to store some general values, including a dataversion number. I check that number when I open the database, and if it is less than the current version, I do an upgrade.
Instead of creating a table, you could also use sqlite's built-in user_version pragma to check and store a version number.
You could check the table structure directly: look for the existence of a column or table.
To upgrade:
You could upgrade in place by using a series of SQL commands. You could even store a SQL file inside your app bundle as a resource and simply pass it along to sqlite3_exec to do all the work. (Do this inside a transaction, in case there is a problem!)
You could upgrade by copying data from one database file to a new one.
If your upgrade may run a long time (more than one second), you should display an upgrading screen, to explain to the user what is going on.
1) The database file isn't stored as part of the app bundle so no, it won't get automatically overwritten.
2) Yes - all their data will be saved. In fact, the database won't get touched at all by the update.
3) This is the tricky one - read this fantastically interesting document - especially the part on lightweight migration - if your schema changes are small and follow a certain set of rules, they will happen automatically and the user won't notice. however, if ther are major changes to the schema you will have to write your own migration code (that's in that links as well)
I've always managed to get away with running lightweight migrations myself - it's by far easier than doing it yourself.
What I do is that I create a working copy of the database in the Documents directory. The main copy comes with the bundle. When I update the app I then have the option to make a new copy over the working copy, or leave it.
I'm updating an app to a whole new version (remade). Everything is going to change to be faster and less bugy. As other post suggest I cannot create another version of the model since I don't have the app code to the previous version (I started a new project). All I have is the bundle identifier for it to be an update. I will use core data but I want to delete all the old models and old data for the users that are updating, as if they deleted the app and reinstall it. How do I achieve this? or there's no need to delete anything because is a different model? All i want is to prevent app crash on launch. thanks in advance.
If you tried to open the same persistent store file with a model that doesn't allow Core Data to make sense of it then you'd raise an exception. So probably all you need to do is use a different file — remember that you get to specify the on-disk location in addPersistentStoreWithType:configuration:URL:options:error: — for your persistent store and ask NSFileManager to delete the old one.
I don't think there's a penalty for asking to delete a file that already doesn't exist so no need for any particularly complicated logic. You'd just be duplicating what the file manager does internally anyway.
Alternatively, if you prefer to keep the same file, enclose your call to addPersistentStoreWithType:... in an #try/#catch block and in the #catch just delete the existing file and try the addPersistentStoreWithType:... a second time.
I have app in that i am using coredata. And when i install the app three files are getting created in the document directory called “test.sqlite, test.sqlite-shm and test.sqlite-wal". And now in second app i copy the test.sqlite in the folder and i want to access the database and tables but i got error like this "no such table found". Is there any issue that i create the database with coredata? please help me.
You either need to:
send all of the sqlite* files that Core Data creates
export the content from the data store, format it and send that
Option 1 should work and be fast to implement, but it isn't very future proof. Option 2 will take longer but is a much better solution.
I have a pretty strong background in C++ and am making the switch to Objective-C to try to make an iPhone app. A main component of my app will be a database.
1) Is there a way to update the database of the app without requiring users to update to a new version from the App Store?
2) If there is, where & how do you pull the data into your app? Do you have to pull it from a website?
2a) Is there a way to make a master copy of the app that I can make data changes in and then have that copy update all other versions of the app?
If my database contains info that is only updated by me, do I need to store each piece of data as an object?
Ex: One "object" may have a name, a type, a number, and a picture
names, and types will overlap but numbers and pictures will be unique
Thanks again.
Yes, copy the datdabase (SQLite) from the application bundle to the documents folder. For an update, download over top the old one. Also, you can use something simpler than a database like an NSDictionary stored in a .plist file.
Yes, from a web server. NSDictionary has methods that let you download directly from a URL (dictionaryWithContentsOfURL). So does NSData.
Why not use third party tools to edit data? You can store a NSDictionary in a .plist file and edit it there, then upload it to the web server.
I have the task to re-engineer an iPhone app which makes use of Core Data to store some values. Unfortunately I do not have access to the original source code but I do have acces to old database files, copied directly from the device where the old version of the app is installed.
I have to create a new version of the app with some new functionality and I am trying to import the data from the Sqlite Db and migrate it to a new version.
I am already failing at the task to read the data from the old database. Though I can open the Sqlite file and such was able to exactly reproduce the data structure in my own datamodel, everytime I try to read the data, it fails with a
Can't find model for source store
error.
Ignoring the old data is not an option because there is important data stored there.
I googled for solutions and tried every recommended solution related to migrating data but it all fails. Maybe I can not use the Sqlite created by another app? Or so I overlook something in re-engineering the structure of the datamodel even when I used exactly the some field names and datatypes? Is there another way around this?
I could not solve the issue but I found a workaround. By using Sqlite directly, I was able to query the legacy data and import it into my newly created data model. A good starter point for using Sqlite is here:
http://www.techotopia.com/index.php/IOS_4_iPhone_Database_Implementation_using_SQLite