Am developing an application using core data. Every time I delete the application from the emulator all the data that was inserted using core data is deleted. does this mean when i publish my application my data base will be empty? I want the data base to have values when i publish it or install it to anther device.
You can create a database and package it inside your application bundle for distribution. Then, whenever your application starts up, before using any data it can check to see if there's a copy of the database in the working directory. If not, it should copy the packaged one.
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I am using phonegap for IOS app development. Now, phonegap tries to find the db by default in 'NSCachesDirectory', but whenever IOS runs into memory problems, it tries to delete data from 'NSCachesDirectory', so, the data is not secured. If i am not mistaken, this problem was solved in cordova 2.1.0, where the back-up of data is taken and then restored afterwards. So, just wanted to confirm if i am heading in the right direction or data itself can be stored in 'NSDocumentDirectory' so that data is secured and somehow phonegap looks for db in 'NSDocumentDirectory' and not Caches direcory. Thanks.
Only documents and other data that is user-generated, or that cannot otherwise be recreated by your application, should be stored in the /Documents directory(You can store DB in Documents directory)
Data that can be downloaded again or regenerated should be stored in the /Library/Caches directory.
I've been working on this problem for a while now. Here's what happens:
My app is launched. It already has existing data in the core data store. It then connects to Dropbox using TICoreDataSync.
Then I connect a second device, which also has existing data. I connect it up to Dropbox the same way.
What then happens is that when I sync, it syncs data between the two harmoniously. Any changes i make on one device are sent to the other after a sync on both devices. The problem is, I want the existing data in the database to be uploaded to Dropbox and included in the sync, so both devices have all data.
How can I do this?
This is actually not how TICoreDataSync was intended to work. It will not merge those two store files for you, but will rather pull down the store file uploaded by the first device to the second device and then keep those store files in sync. From your description it sounds like you are skipping the whole store upload and download steps during sync manager registration.
I want to create a large database. I am thinking of using core data for this purpose.But i want to insert the data to it manually and only once. This data is never deleted or edited but only read. How can i use core data to add such large number of objects to database? How to create database in core data and write only once.
Your question is quite general but I'll try to give you some hints on it.
Based on my experience, the simplest way to achieve it, it's to follow these two steps:
1) You could create an external file, in XML, JSON or plist format, that you can parse and use to create a prepulated a Core Data store. You can find some info in core-data-tutorial-how-to-preloadimport-existing-data-updated. In particular, you could set up a dummy project (or just use the AppDelegate methods) and use it to create the store, e.g. MyDataStore.sqlite.
2) Once you created, forget about the routines you have previously used and you ship the store in the application's bundle of your app. There the store is read-only. Otherwise, if you need to modify it, you are not allowed to do it and so you need to move it, for example, to the document directory.
You cand find additional info in the following SO topics:
Is Core Data useful for readonly data too?
How can I ship my app with a pre-populated Core Data database?
Core Data Store included in App Bundle
P.S. If you are in production and you need to make same change to your store, you need to republish the app (since the store is within the main bundle). To avoid this you need to move the store to a different directory and set up, for example, a sort of sync mechanism.
Hope that helps.
It would be useful for many people to know how to completely remove an application from your device when testing.
I have downloaded my app many times now, and likewise have deleted it many times. The problem is when deleting the app, it does not remove things like the persistent object related to my app, or the images downloaded through the app. So, when I download the next build, I have no idea if something broke that is related to building the persistent object or fetching the images since those elements already exist from the last build.
I don't know if this is a cache thing. I don't know if this is expected and I have to use some utility to wipe this data after deleting the app. I can't really find much info through basic web searches.
Any information would be appreciated.
Blackberry Bold 9000. 4.6 OS. tested with both SD card and no SD card.
Objects stored in the PersistentStore are automatically deleted on uninstall if their interfaces were defined in your project. If they are from the standard BlackBerry API then they will stick around until they're deleted. E.G if you save a String in the PersistentStore it will stay in the PersistentStore but if you save a class you created it will be deleted on an uninstall. So if you want to have those objects be deleted automatically just create a wrapper class and save that.
Images stored on the filesystem will not be deleted until you or some application deletes them. However, it should be easy for you to write an app that clears everything out.
Another solution you could implement is making your app somewhat self-aware of its data.
Create a simple String value that you persist (or optionally, persist it in a Hashtable so you can store many properties this way) that includes "Version".
At startup of the GUI app, compare the stored "Version" against the application's current version. If the stored version doesn't exist, or if it exists and matches, take no action.
If it exists and does not match, automatically clean up old persisted data; or alternatively prompt the user to see if they want that data to be deleted (which one is better will depend on your implementation)
You can also use CodeModuleListener to listen for an uninstall event -- when that happens, you can clean up at that time as well or instead.
(As an aside and a bit of shameless self promotion, I am actually currently working on a shareable library for Blackberry that makes managing persistence much easier, as well as desktop data backup/restore. I'm doing this as part of the BBSSH project, but I'll be splitting it off into a separate library of core components and publishing it under a dual GPL/optional commercial license. It will contain hooks for data cleanup and data versioning. )
I developing an app that is read-only. The data has relationships, so I cannot just use a plist or something similar.
Questions:
Should I use Core Data for such a requirement?
If so, how would I enter the data and then release the app with that data?
How would I make it so that the app doesn't need to re-populate a DB every time it loads?
Is there a way to create a Core Data model using sql commands with sqlite (i.e. insert into, etc)?
You may use an SQLite database to accomplish this.
Create the model in your iOS app.
Create and populate the database in a Mac OSX utility command-line app
Copy the sqlite file into your iOS app and link it with some code
Work through these two tutorials, line by line, and afterward you will have a good enough understanding (and code sample) to complete this task in your own app.
Core Data on iOS 5 Tutorial: Getting Started
Core Data on iOS 5 Tutorial: How To Preload and Import Existing Data
In my short experience with the iPhone, you have two options.
Write a data import function and run it on the first application launch.
Use solution 1, but build the initial sqllite file in the simulator, and then on first application launch, copy it into the app's documents directory.
From past experience, option 2 is much quicker for user experience, and the preferred solution.
You can write a utility project that imports the app's data model and use throwaway code n that project to populate the Core Data DB. Once the DB is populated, simply copy the actual file to the app project's resources folder and then when you set up your persistent store, use NSBundle to return the path to the DB file within the built app.
And you're done.