Re: Using an auto incremented NSNumber as attribute in a NSManagedObject
Re: Using an auto incremented NSNumber as attribute in a NSManagedObject
- Subject: Re: Using an auto incremented NSNumber as attribute in a NSManagedObject
- From: "Hank Heijink (Mailinglists)" <email@hidden>
- Date: Thu, 6 Mar 2008 16:12:13 -0500
It's a little busy at the developer website, since they just announced
the iPhone SDK. I think there's nothing to do but wait...
Best,
Hank
On Mar 6, 2008, at 4:05 PM, Joshua Preston wrote:
Hey guys,
First, let me say that I'm just starting to pick up Cocoa and
Objective-C, and so far, I love it. Core Data seems to be an
elegant solution to some of my past problems (mainly Java
persistence). I am however having problems finding information
regarding auto incremented attributes, namely an NSNumber
attribute. I've created the attribute with the Data Modeler and set
up all of the relationships I require. Everything worked, so I read
about implementing a subclass of NSManagedObject and defining a -
awakeFromInsert method. This appears to be working for some of the
other fields, such as the date, but I'm having problems determining
how exactly to increment the number.
For example, when I create my first object, I want the numeric id
field to be 1. Each subsequent insert should be the previous
numeric id field + 1. I've read some of the posts regarding
performing this and the general thought on this process is to create
an additional entity in my data model containing the "current
maximum index" then perform fetch, increment and get value of that
field and use that for the incremented value of my new object. I'm
not sure if this is still the only way or even the preferred way to
perform this feat. I'm kind of worried about locking that "counter"
field until the new managed object has been created to avoid any
increment problems.
Additionally, I've tried accessing the docs located at the link
below, but I keep getting connection errors, anyone else having
problems accessing the documentation?
http://developer.apple.com/documentation/Cocoa/Reference/CoreDataFramework/Classes/NSManagedObject_Class/Reference/NSManagedObject.html
Regards,
Joshua Preston
email@hidden
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