Question

I have a few NSManagedObject classes. I am pulling down some JSON data from a server which I parse into an NSDictionary object. When the conversion from JSON to NSDictionary occurs, all of my data is cast as NSStrings. When I then map this dictionary to my managedObject I get this:

Unacceptable type of value for attribute: property = "idexpert"; desired type = NSNumber; given type = __NSCFString; value = 1.'

So my managedobject is looking for an NSNumber but it’s getting a string and throwing an exception

Is there a way that when I call setValuesForKeysWithDictionary I can automagically cast the values properly for the managedobject they are going into?

Thanks!

Answer 1

If the json you are receiving actually has number values and they are getting cast as string you should get a new json parser. I recommend NXJson. Otherwise there wont be any magical casting happening.

If the json is returning strings such as {“idexpert”:”1″} then you can override setValuesForKeysWithDictionary and do something like the code below;

-(void)setValuesForKeysWithDictionary:(NSDictionary *)d{
   NSMutableDictionary *newDict = [NSMutableDictionary dictionaryWithDictionary:d];
   NSString *value = [newDict valueForKey:@"idexpert"];
   [newDict setValue:[NSNumber numberWithLong:[value longValue]] forKey:@"idexpert"];
   [super setValuesForKeysWithDictionary:newDict];
}