Mapping an NSArray of NSDate with RKObjectMapping - objective-c

Question

Suppose I have this Json :
{ "arrayOfDates" : [ "7-28-2013", "7-29-2013", "7-30-2013"]}
And my object is :
#interface MyObject : NSObject
#property (nonatomic, retain) NSArray* dates;
#end
I tried to map the arrayOfDates with dates.
RKObjectMapping* mapping = [RKObjectMapping mappingForClass:[MyObject class]];
[mapping addAttributeMappingsFromDictionary:#{#"arrayOfDates" : #"dates"}];
NSDateFormatter *dateFormatter = [NSDateFormatter new];
[dateFormatter setDateFormat:#"MM-dd-yyyy"];
mapping.preferredDateFormatter = dateFormatter;
The mapping result was an array of NSString !
Is that a way to get an array of NSDate instead of NSString ?

Answer 1

You can't get RestKit to do it. Instead, iterate over dates in the completion block called by RestKit and use your formatter to convert the strings, then update dates.
RestKit usually translates the string to a date if the destination property is an NSDate, but in your case it's an array so RestKit doesn't know that it should be transformed.

Answer 2

I came across this answer trying to solve a similar problem. I found a way to get RestKit to do this using a custom RKValueTransformer.
RKObjectMapping* objectMapping = [RKObjectMapping mappingForClass:[MyObjectWithAnNSArrayProperty class]];
RKAttributeMapping* datesAttributeMapping = [RKAttributeMapping attributeMappingFromKeyPath:#"arrayOfDates" toKeyPath:NSStringFromSelector(#selector(myArrayOfDates))];
datesAttributeMapping.valueTransformer = [RKBlockValueTransformer
valueTransformerWithValidationBlock:^BOOL(__unsafe_unretained Class sourceClass, __unsafe_unretained Class destinationClass)
{
// We transform a `NSArray` into another `NSArray`
return ([sourceClass isSubclassOfClass:[NSArray class]] &&
[destinationClass isSubclassOfClass:[NSArray class]]);
}
transformationBlock:^BOOL(id inputValue, __autoreleasing id *outputValue, Class outputValueClass, NSError *__autoreleasing *error)
{
// Validate the input and output
RKValueTransformerTestInputValueIsKindOfClass(inputValue, [NSArray class], error);
RKValueTransformerTestOutputValueClassIsSubclassOfClass(outputValueClass, [NSArray class], error);
NSArray* inputValueArray = inputValue;
NSMutableArray* result = [[NSMutableArray alloc] initWithCapacity:inputValueArray.count];
// Convert strings to dates
for (NSString* inputDate in inputValueArray)
{
[result addObject:RKDateFromString(inputDate)];
}
// Get a non-mutable copy
*outputValue = [result copy];
return YES;
}];
[objectMapping addPropertyMapping:datesAttributeMapping];