Re: Core Data copyWithZone error (NSData encoded structs as attributes)
Re: Core Data copyWithZone error (NSData encoded structs as attributes)
- Subject: Re: Core Data copyWithZone error (NSData encoded structs as attributes)
- From: Soares <email@hidden>
- Date: Thu, 26 Apr 2007 17:07:39 +0100
Yes, I could do that, which is probably the best way to go in the long run.
But I need to be able to store a primitive C float array in my Entity as an
attribute. Has anyone done this before?
On 26/04/07, Jon Trainer <email@hidden> wrote:
Instead of storing a serialized struct, could you replace your struct
with a Core Data NSManagedObject (entity)? Then store the data as 1-
to-1 relationship to your parent entity. Seems this would simplify
the work you need to do.
- Jon
On Apr 26, 2007, at 11:18 AM, Fen Soares wrote:
> Hi list,
>
> I'm using a custom object as one of my Core Data attributes. I'm
> using the
> http://developer.apple.com/documentation/Cocoa/Conceptual/CoreData/
> Articles/cdNSAttributes.htmldocs
> as a guide on how to do this, because my attribute is a non-supported
> type (basically its a class that contains a c-struct)
>
> In my NSManagedObject subclass I implement the awakeFromInsert
> method to
> create a new instance of the object that represents my attribute
> and then
> try to use:
>
> -(void)setMethod(myCustomObject*)value
> {
> [self willChangeValueForKey:@"attr"];
> [self setPrimitiveValue:value forKey:@"attr"];
> [self didChangeValueForKey:@"attr"];
> [self setValue:[NSKeyedArchiver archivedDataWithRootObject:attr]
> forKey:@"attrAsData"];
> }
>
> My custom object contains a single data member which is a struct,
> and the
> error I'm getting is:
>
> -[myCustomObject copyWithZone:]: selector not recognized [self =
> 0x3a5010]
>
>
>
> All I want to do is to be able to store custom objects in my Core
> Data Model
> that contain structs, or more simply. I'd like to have attributes
> in my
> entity that are NSData encoded c-structs (as I believe this is the
> only way
> to make them persistent using Core Data).
>
> I'm using a Obj-C wrapper around my struct at the moment, due to the
> accessors requiring a custom object pointer. I'm new to this so
> could be
> making a real mess of it. Any clarification would be appreciated.
>
> Thanks.
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