How to deal with an empty object {} in RestKit - objective-c

Question

The response I sometimes get from the server is a JSON representing an empty object like this {}
I've read this question/answer over here already, which states I should implement the willMapData delegate function and point the *mappableData somewhere else. The thing is I can't figure out what should I assign to *mappableData so that my app won't crash.
I've tried this
- (void)objectLoader:(RKObjectLoader *)loader willMapData:(inout id *)mappableData
{
id<RKParser> parser = [[RKParserRegistry sharedRegistry] parserForMIMEType:RKMIMETypeJSON];
*mappableData = [parser objectFromString:#"{\"unknownObject\":\"\"}" error:nil];
}
But nevertheless my app crashes with a rather pissing
'NSInvalidArgumentException', reason: '*** -[__NSPlaceholderDictionary initWithObjects:forKeys:count:]: attempt to insert nil object from objects[0]
Can you help me out?
UPDATE
Turning on RKDebug messages gives me this in the console:
Performing object mapping sourceObject: {
}
and targetObject: (null)
then the code reaches RKObjectMapper.m:
if (mappableData) {
id mappingResult = [self performMappingForObject:mappableData atKeyPath:#"" usingMapping:mappingsForContext];
foundMappable = YES;
results = [NSDictionary dictionaryWithObject:mappingResult forKey:#""];
}
but mappingResult over there comes back nil... so the app crashes when it tries to create an NSDictionary with a nil object.

Answer 1

Break up the assignment into two lines.
SomeDataType *object = [parser objectFromString:#"{\"unknownObject\":\"\"}" error:nil];
if(object){
*mappableData = object;
}else{
// You've got nil, do something with it
}
Now you can check for nil values and take the appropriate action. What that action is depends on the context of the crash.