I'm working on an iPhone app that uses NSURLConnection to down load files and then convert those files into sqlite3 tables. I would like to use core data to store these tables and to create all the applicable objects. So, do I have to build the models of the data in XCode with the graphical tool representing all the table names and columns? I've been searching and found examples of apps that use core data and copy in a pre populated sqlite file for the default data. The data that I'm working with will have some variations in the table names and column name and types. Any direction would be appreciated.
You need to load the database via a Core Data model within a Core Data application. You can't use a sqlite database that was not created with Core Data (without a huge amount of unsupported pain).
Core Data databases created with applications on Mac OS X are compatible with Core Data applications on iOS. I know of a number of developers that have written little command line tools that run as a part of building their iOS application that effectively "compile" a database that is then copied into the application's app wrapper.
Related
I am developing iPhone app for a web application currently running online. Current web application is big and complex and uses SQL to store vital information like member details, login credentials etx. Other stuffs like info about several sections, groups, sub groups and other information related to each are saved in txt. Current system uses its own standard to keep data in files and also made custom algorithm to read and write data in it. Each txt file is below 1 mb size. There are lot of data manipulations going on.
Custom algorithm created just read those files and put all data in cache as records (same as in core data managedobjectcontext) and whenever there is a change in data the whole file is overwritten.
So while implementing the same what I want to choose for iPhone app? In apple website they said that 'SQLite is perfect for low-level relational database work' https://developer.apple.com/technologies/ios/data-management.html But in my case it is high level.
So please help me to make a decision. Do I want to manage data in files or sqlite database using core data?
I would also like to know whether it is possible to import those classes and algorithms currently in webserver to iOS, so I don't want to rewrite the same algorithm for iOS? Current server codes are in C#
In the rare case that you need to do low-level relational database work use SQLite. In the 99% other cases use Core Data. Don't ever store relational stuff into txt files. It'll just be a pain.
Your use case sounds like a good match for Core Data.
Often misunderstood, Core Data is an object store that happens to use sqlite for persistence. You don't manipulate the sqlite underneath it, Core Data manage the sqlite for you. You do not write SQL. The closest match to it in .NET is EDM and the Entity Framework in ADO.NET.
Assuming the classes and algorithm you want to import in the webserver is in C#, sadly those needed to be ported to Obj-C.
Two questions about Core Data:
1. Is it possible to see the actual data(the db tables) that is stored when using core data?
2. When using the iPhone simulator i can delete the core data db by resetting the simulator. But how can i delete the core data db when using a real device?
Your Mac comes with a command line tool sqlite3. You can use it to do queries against the core data database. Not sure if that violates any rules against reverse engineering that might exist in any license agreements.
You can delete the db for convenience during development by deleting your app from the device and reinstalling it. If you don't want to do it by deleting the app, you will have to write some code in your app to delete it I think.
You can directly view an sqlite store using any sqlite tool including the command line sqlite3 tool. However, (1) Core Data uses a custom undocumented schema so looking at the store doesn't tell you much and (2) the structure of the sqlite store file itself has little relationship to how the managed objects behave in memory. Core Data isn't an sql wrapper. It just takes the managed objects apart to store them in SQL. SQL is just an option and Core Data works fine without it.
To "delete the core data db" you simply delete the persistent store file. Look where you initialize the persistentStoreCoordinator (in the Xcode templates, it's in the app delegate.) The URL for the persistent store/s will be there. Just close down the Core Data stack and then delete the store file with NSFileManager. Then restart the Core Data stack.
I have a simple table that I'm pulling from our existing sql database. Its just a 1mb Vehicle table. It contains enough information that I don't want to create it from scratch, but I can not find a definitive answer on how to import this table into my sqlite environment on the mac.
I've seen a few posts about python scripts that import to Core Data but I don't think thats the way to go.
The table I saved out as .rpt file. Any direction other than the one I'm traveling would be great.
The most correct (and pretty easy) way to do this is to write a little Mac OS X command line tool program that reads the data from your SQLite database and uses Core Data to load the data into a Core Data persistent store.
That persistent store -- the resulting Core Data schema'd SQLite file -- can be added as a resource to your iOS app project and it'll "just work".
Checkout Christian Kienle's Core Data Editor, which let's you import data from CSV files into Core Data: http://christian-kienle.de/CoreDataEditor
It is also useful after the data is imported for debugging.
So I have a question about the ideal setup for an app I am getting ready to build. The app is basically going to be a memorization tool and I already have an sqlite database full of content that I will be using for the app.
The user will navigate through the contents of the database(using the uipickerview), and select something for memorization. If that row or cell of data is selected, it is put into a pool or a uitableview that is dedicated to showing which items you have in your "need to memorize" pool. When you go to that tableview, you can select the row, and the actual data would be populated. All information in the tableview would be deletable, in the event that they don't want it there anymore...
Thats it.
I know that with database interfacing, there are a few different options out there, in this particular setup, is core data the easiest approach? Is there any other way that would be better? I am just kind of looking for a point in the right direction, any help is greatly appreciated!!
Core Data is going to be the easiest. You will want to migrate your data from your raw SQLite file to a Core Data generated SQLite file as Core Data is designed to manage its own file 100%. Fortunately you can do this with a quick command line app on the desktop and then copy the resulting Core Data Sqlite file into your application bundle for later use on iOS.
Doing raw SQLite on iOS is possible but a real headache to get right compared to the ease of use that Core Data offers.
Update
Core Data on iOS produces identical files to Core Data on the Desktop. Therefore you can develop a quick and easy app for the desktop that say for example takes the following inputs:
Table/Entity Name
CSV of a row of data
Then it would create a Core Data entity based on the entity name and insert the data into that row.
With that in place it would be trivial to do a bash script to loop through the all of the tables and the rows in those tables to create your new SQLite file.
Hmmm, might have to do a blog post some time on CIMGF about this :)
I'm diving in to iPhone development and I'm building an iPhone app that uses the Core Data framework and my first task will be to get the model setup with a view that will display it. Thus far, I have the model defined and my Managed Object Files created, but I don't have a database with any sample data.
What's a quick way to create a DB that conforms to my schema?
Are there any tools that can generate a sample DB using my schemas? Or do I have to create this sample data by hand?
Once the DB is created, are there any good tools I can use to directly manipulate the data in DB for testing purposes?
Thanks in advance for your help! I'm going to continue researching this question right now.
This is very close to the question "Provide Base Data for Core Data Application?" Additionally, my answer to this question describes how you can quickly build a Mac application that lets you create or edit a Core Data database that is compatible with your iPhone application's data model.
Beyond that, you can use the application Core Data Editor to do what its name describes.
I assume you've already created a working app that uses sqlite as persistent storage for your data model.
Have a look into the AppDelegate.m file to search for the sqlite database name and location, then run your app in the iPhone Simulator.
Use Spotlight to search for the SQLite database created by the app in the simulator, usually this is /Users/<Username>/Library/Application Support/iPhone Simulator/User/Application/<Application GUID>/Documents/<database name.sqlite>
Now you only have to copy that file to a working folder, open it using sqlite3 (www.sqlite.org), then type .schema to retrieve the database schema.
Now populate it, either by hand or using a python/ruby/whatever script!
Unfortunately, i'm not aware of any tool that will populate a db by simply feeding them the schema.
For directly manipulating the data, sqlite3 provides you with a command line utility that's really handy for that purpose.
When you're finished, add the file with sample data to your App project.