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POCan transformable attributes in Core Data entities be pointers to c structs? My transformer is not being called
 

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  1. POCan transformable attributes in Core Data entities be pointers to c structs? My transformer is not being called
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    <p>I'm trying to make a CoreData-persisted entity. This entity has a few properties, one of which is a non-standard attribute, state. The state attribute is a pointer to a C struct with a few properties in it. Here's what my data model looks like:</p> <p>Entities:</p> <p><strong>MDInstance</strong></p> <p>Attributes:</p> <ul> <li>duration: Integer 16</li> <li>moves: Integer 16</li> <li>name: String</li> <li>state: Transformable. I set the Transformer to MDStateTransformer.</li> </ul> <p>I generated my class and edited the state property. This is what the interface looks like:</p> <pre><code>#import &lt;Foundation/Foundation.h&gt; #import &lt;CoreData/CoreData.h&gt; #import "MDState.h" // this is where the State structure is defined @interface MDInstance : NSManagedObject @property (nonatomic, retain) NSNumber * duration; @property (nonatomic, retain) NSNumber * moves; @property (nonatomic, retain) NSString * name; @property (nonatomic) State *state; // note that this is a pointer to a struct @end </code></pre> <p>This is what the implementation looks like:</p> <pre><code>#import "MDInstance.h" @implementation MDGameInstance @dynamic duration; @dynamic moves; @dynamic name; @synthesize state; @end </code></pre> <p>I created a value transformer called MDStateTransformer. The implementation of this is (probably) not important. Suffice it to say I have <code>allowsReverseTransformation</code> returning <code>YES</code>, <code>transformedValueClass</code> returning <code>[NSValue class]</code>, and I've implemented <code>transformedValue:</code> and <code>reverseTransformedValue:</code></p> <p>Lastly, I registered the MDStateTransformer in my AppDelegate's <code>application:didFinishLaunchingWithOptions:</code> like this:</p> <pre><code>MDStateTransformer *transformer = [[MDStateTransformer alloc] init]; [NSValueTransformer setValueTransformer:transformer forName:@"MDStateTransformer"]; </code></pre> <p>If I create a new instance of my MDInstance, set it's attribute -including the state attribute- and then try to save the entity, my transformer is never called. </p> <p>I put a stop point in my transformer's init method and it is being instantiated. I put another in <code>transformedValue:</code> and it the function is not being called.</p> <p>However, if I update my MDInstance so that the state attribute is not a pointer, but is simply a State structure, and I update the transformer to work with a struct and not a pointer, the <code>transformedValue:</code> is called.</p> <p>Is it possible to have a custom attribute on an object which is a pointer to a c struct? If so, any ideas what I'm doing wrong?</p>
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