Re: Referencing known values in core data
Re: Referencing known values in core data
- Subject: Re: Referencing known values in core data
- From: "I. Savant" <email@hidden>
- Date: Wed, 13 Aug 2008 06:17:02 -0400
On Aug 13, 2008, at 5:34 AM, Andrew Zahra wrote:
I am experimenting with core data. Binding fields such as text
fields works
fine. But now I have a pop up menu I want to bind to a set of known
values.
I have a "Task" Entity with a "frequency" field. The frequency field
is a
set of known values, such as hourly, daily etc, so I have not put
this in my
model as a separate entity. What is the correct way to handle this
situation
so the value of the popup menu gets saved and loaded from the core
data
store?
One way to do this (the way I usually do it) is to:
1 - Define somewhere a lookup list based on numbers.
(example: [NSNumber numberWithInt:1] represents "hourly", 2 is
"daily" ...)
2 - In your entity, specify your 'frequency' attribute as one of the
integer types.
3 - For each popup that uses this list, create an item for each word
(hourly, daily, ...) by hand, setting each item's tag to the number
that represents that item.
(example: set the "hourly" item's tag to "1")
4 - Bind the popup's "selectedTag" to your Task entity's 'frequency'
attribute via some controller.
That's it. You may wonder why I don't just suggest using the
'selectedIndex' binding. Simple: you may some day want to insert
"weekly" between "daily" and "monthly". That would cause problems with
existing user data since the indices would change. Via the tag method,
you can reorder / insert menu items at will.
--
I.S.
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