I have a core data entity with a property amount, which is a NSDecimalNumber. For this property the entity's class has a method defined with an NSDecimalNumber as argument.
In Interface Builder I bound a table column to this property (using an NSArrayController) and on the column's cell I put an NSNumberFormatter. The formatter is configured in IB as 'currency'.
Now, when I try to enter a number, I get the following error:
-[NSCFNumber decimalNumberBySubtracting:]: unrecognized selector sent to instance 0x1001d5590
Apparently my setter method is receiving a regular NSNumber rather than an NSDecimalNumber. Can I configure my formatter differently, perhaps in code rather than IB, or is the only option to add an additional setter with an NSNumber as argument?
It's not clear to me exactly where your issue is. Either the formatter is giving you a straight NSNumber instead of a NSDecimalNumber or the core data is.
To make the NSNumberFormatter give you NSDecimalNumbers, use the method -setGeneratesDecimalNumbers:
To make the data store give you NSDecimalNumbers, make sure the relevant attribute in the model is set to "decimal number".