Question

I’m trying to figure the best approach to solve this problem.

—

I have a “History” table that,
lists ALL years that have data.

If a user clicks a given Year, it segues to a new Table and,
lists ALL months that have data.

Clicking a given month, shows a new table that,
lists ALL days that have data.

Clicking a specific day, shows a list of one or multiple Time Stamps.

—

What is the best approach to solve this?

If user creates a Time Stamp. I need to insert it with today’s date.

I also need to have the ability that if a user,
Deletes a given year. Everything in that year is deleted.

That same way,
Deleting a month, deletes everything in that month, for it’s particular year.

And so on, to the point where the user should be able to delete Individual Time Stamps.

—

I thought I would Use a Dictionary with key for the “year”. 2012, 2013, …

And each retrieving another Dictionary with key for the “month”, 1, 2, 3, 4, …

And so on … and so on …

I also thought I could make a model using Core Data.

A Class Year representing the “Year” entity, having a relation to many possible Months, and each month, having a relation to many possible days, and days to Time *Stamps*.

And last,

I thought of creating a model with only two Entities.

Entries, with only one attribute “Date“, that has a to-many relationship to “Time Stamps“, receiving All the possible Time Stamps for that given day.

I am new to iOS programming. So this is all theory for me. But I did follow some Core Data tutorials and others working with NSDictionaries, protocols delegates and so on.

The “Dig In” approach as I go trough, seems more elegant. Specially because I think I could delete a particular given object in a cascade manner?

Do any of these make sense? Or is there a more obvious easy way to go about it? Also, please consider in the answer what would be easier to implement if a user chooses to delete a given entry in the “tree”

Any help is most appreciated.

Thank you advance!

Nuno

Answer 1

If you are going to rely on Core Data or any database engine, the best way to solve this is to use the database itself.

I see two possible solutions (there is more of course). The first, the simplest :

Entity
- timestamp
- year
- month
- day
- all_the_stuff_you_need

Make year, month and day readonly, updated along timestamp. Indexes: year, year+month, year+month+day. Easy call.

That way, you can very simple query the database, asking it to return the entities you need and only the entities you need.

A more complex setup would be:

Entity
- timestamp
- all_the_stuff_you_need
- year -> Year
- month -> Month
- day -> Day

Year
- year
- entities ->> Entity

Month
- month
- entities ->> Entity

Day
- day
- entities ->> Entity

So basically, 3 data domains for the years, months and days, months and days being immutable.

That structure is more complex, but it gives a better view of your data. You have a direct access to more information on your data as the data domains are explicit and well defined.

A third solution would be to create a date entity with year, month and day, with one entry per day. A middle ground between the two solutions above. Less interesting I think, but hey, it may suit your needs anyway.