I know there are similar questions on this subject but nothing that quite answers my query. I am aware that it is a bit of a newbie question!
I have an app on the AppStore which I will soon be looking to update. My binary contains a pre-loaded sqlite file with a list of data which the user starts off with. However, the user will extensively edit this information and it is crucial that that data is maintained through the update.
I am not changing the CoreData structure at all so won't be performing any migration but my concern is that when I upload the new binary the packaged sqlite file will overwrite the users existing data. I suspect that won't be the case but can anyone shed any light on it?
When updating an application the documents directory is untouched. Presumably your startup code checks to see if you have already copied the initial database from the bundle to the documents directory - this will work the same way after an upgrade.
You are testing this every time you run a new build on your device during development anyway - you've put a whole new version of the app bundle on there, and it doesn't kill all your data, does it? (does it???)
Related
I'm working for an iOS app that was earlier developed using phone gap. It is having a sqlite database for storing data. But now while developing the same app in native, I'm using core data for storing the data.
Now when the new native app replaces the old phone gap app on user's device, I want to copy data from already existing sqlite file into core data.
So when I run the application on device with phone gap build pre installed my app(native) replaces the old build as I'm using same bundle ID but I'm not able to find out the path to that sqlite file. Does sqlite file still exists in documents directory?
If you have an example old database file still installed on one of your devices you could try downloading the App off the device using the Device manager in Xcode.
Then you open up the bundle and search for your file. Then if you know its location / name you can simply access it, read it using some SQLite library and load the data into your CoreData backing store. Keep in mind you either want to mark it in NSUserDefaults or delete the old DB all together so your app does not keep on migrating ( And then maybe accidentally deleting new data from a user. ) I would choose for keeping the old one around for at least a version or 2 so you can verify that your migration works without bugs / deleting user data in the process.
Tip: It is probably a good idea depending on how big your database is to show the user some kind of progress or "migrating / optimizing db" while you're doing this. So you don't end up with the user adding more data to the database before you're done migrating.
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.
My app have too much dynamic app resources like images, html+css and xml or json files..that can be updated, So I cannot put these resources in app bundle it will not get updated once on app store i need to have it updated there...secondly i also cannot put these resources on server where I can request the content from server every time i need it...
So my question is that is good to store data locally in document directory??? how does apple app review team will react to it? I have heard that there is an iCloud problem while putting data in document directory is it right?
So where to store data of iOS application locally on device?
Thanks in Advance.... Looking for some good solid answer!
This kind of data should be copied to ~/Library/Application Support. See the File System Programming Guide for full details on where everything goes and how it will be treated.
You may want to consider having the initial assets you are referring to be resident in your application bundle. And then when you have updated versions, save them in your Documents directory (or any legal path you want).
The reason for this is for failover, in case there is a problem, it allows you to revert back. When you are dynamically loading content, you have to factor in you can encounter various problems during a download such as corrupt data or even a dependency not being downloaded yet.
FWIW, I implemented this for a game that supported dynamic loading of content. The bundle had the original assets. There was a temp download directory. When data was validated, it was moved to a locale where it was consumable. On app start, the first step was to just copy the data from the bundle to the consumable directory. While it seems perhaps wasteful and several steps, it worked surprising well and most would not even know this sort of thing was happening.
I am updating an old iOS app which used sqlite database. I changed the database structure adding columns to existing tables. Now, I am testing it on my device. If I clear my old app from iPad and then run this new updated version on it, it is working fine. But if I have the old version installed on ipad already and test this updated version, it is somehow using the old database instead of the one updated. Can some one help me why it is doing this?
My guess and to try and make a simple answer for you is this. It's likely you updated the database in the project file - which means when you run it, your new db will exist in the bundle. files in the bundle cannot be updated, so its common practice to copy the database out of the bundle and store it somewhere in the ios sandbox. I usually use the documents directory to keep it simple.
Most likely what is happening is that when you run it over a pervious install, it see's that the file is already copied over to the device so it does not touch it, however on new installs, it probably sees the database is missing so it copies it there and that is why on new installs it works fine but existing ones it does not.
Look in the app delegate or your root view controller for code that checks for the existing database and copies the database over if needed on startup.
If you need to update the database on existing installs, you would need to force the copy.
Beware though if you have data in the existing database not to overwrite it if its important. If important data is stored there, you have to either do a little shell game of getting the data and importing into the new database, or maybe a simpler way, is to run the database schema modification commands on the existing database so it is the same.
again, beware and make a copy of the local database file before you run those commands, just in case.
best of luck
In iOS, a SQLLite database is really just a file. When you used the old app, it created the schema in the database file. When you load the new app, the data remains, untouched. If you want to use the new schema, you will have to detect the old schema and update the existing data. I believe that there are documented ways to deal with this. Bryanmac's question reference seems to be a good place to start.
When you install a new version of your app, iOS actually installs it in a new directory and then copies the contents of the documents folder from the older version to the one in the newer version. If you want to just use your new db, the best way is to have this db renamed or stored in a different directory inside your app's document store.
Here's a relevant article on updating An sqlite CoreData backing store on iOS:
http://www.musicalgeometry.com/?p=1736
This is the first time I'm developing for iOS. I need my app to ship with a pre-filled sqlite database which a user will read from and write to. How should I go about deploying this? Can experienced developers help me?
What I thought was this:
I create and pre-fill the database in my development machine, add it to my app bundle. During app initialization in device, I check if I have a database in NSDocumentDirectory of my app. If not, I copy the database in the bundle to NSDocumentDirecory and read from/write into it. If I have a db there, I just use it.
Is this a bad idea? Any pitfalls I'm falling in here?
I have an app that does something pretty similar to that. Mine doesn't allow writing to the database, but I don't see why it would be hard.
I have a dataset that I import into a SQLite database, copy it into the apps directory, put the DB filename into a constant and it seems to work really well.
I change the SQLite filename each time I put it in there (MyDB62020111.sqlite -> MyDB62020112.sqlite) just to make sure that I avoid a problem where it thinks that the file is already in the NSDocumentDirectory and not update it.