Confused with a basic idea

[cation007]

Hi,
I am confused with a basic idea.

I have a database and I want to load it and use it in my application.

Application uses navigation controller.

The problem is, when and where should I load the values from the database ?

in application delegate or rootviewcontroller ?

If I do it in rootviewcontroller, everytime I move between different tableviews, the variables get released and the database is loaded again and again.

If I do it in appDelegate, I dont know how to pass the values to the rootviewcontroller.


I want to read the database only once for this whole application.

How can I solve this problem?

How do ppl normally work with databases (i.e, when and where do they read from databases) ?

Thanks for replying.
p.s. Is my question not clear ?

[FlyingDiver]

Your question is clear enough.

The usual method is to have a class just to manage the database. You create an instance of the class in your AppDelegate, and initialize it from the database. Then, any view or controller or whatever that needs access to the data gets the pointer to the Data class from the AppDelegate, and messages that Data class to get the info needed.

That way the internals of the data storage are encapsulated in that one data management class.

joe

[cation007]

Originally Posted by FlyingDiver

Your question is clear enough.

The usual method is to have a class just to manage the database. You create an instance of the class in your AppDelegate, and initialize it from the database. Then, any view or controller or whatever that needs access to the data gets the pointer to the Data class from the AppDelegate, and messages that Data class to get the info needed.

That way the internals of the data storage are encapsulated in that one data management class.

joe

Hi,
Thanks for replying.

I got what you meant. But I still din't understand how it works.

Say for Eg:

I have a model called dataModel. and I create an object and initialize within the appDelegate.

appDelegate.m:
dataModel *dataObject = [[dataModel alloc] init];

Now, how will rootViewController access that object ?

(or)

what should be the code within rootViewController.m to access it ?

am I missing any basics about delegates ?

[nobre84]

Anywhere in your program you can access the delegate with the following:
MyAppDelegate *delegate = [[UIApplication sharedApplication] delegate];
Then you can access your database class from there...

[FlyingDiver]

in your view controller:

dataModel *theData = [[[UIApplication sharedApplication] delegate] dataObject];

Just make sure dataObject has a getter method or you synthesize properties for it.

joe

PS - the convention is to have class names start with uppercase (DataModel, not dataModel).

[cation007]

Hi, problem fixed

By mistake, I was removing all objects in the dealloc method in one of the subviews.

That fixed the problem.

Thanks a lot