Value Transformer Name
Value Transformer Name
- Subject: Value Transformer Name
- From: Richard Somers <email@hidden>
- Date: Fri, 10 Apr 2009 08:15:43 -0600
In an Xcode data model window, a transformable attribute has an input
labeled "Value Transformer Name:".
The Core Data Programming Guide says "By default, Core Data uses the
NSKeyedUnarchiveFromDataTransformerName transformer, however you can
specify your own transformer if you want."
In my test application various values for the "Value Transformer
Name:" in the data model window produce the following error warnings.
1. blank -[NSKeyedArchiver encodeValueOfObjCType:at:]: this
archiver cannot encode structs
2. NSKeyedUnarchiveFromDataTransformerName Warning: no
NSValueTransformer with class name
'NSKeyedUnarchiveFromDataTransformerName' was found
3. NSKeyedUnarchiveFromData -[NSConcreteValue bytes]: unrecognized
selector sent to instance
Questions
Why does number 2 not work when the documentation indicates that it
should and is actually the default condition?
If number 3 is really the same as the default condition then why does
it not produce the exact same results as number 1?
Why does the NSValueTransformer class have named transformers but
those names can not be used in the Xcode data modeler or in Interface
Builder without producing an error?
Richard
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