Question

I have the following class:

@interface Topics : NSObject {
    NSNumber * _until_id;
    NSArray * _topics;
}

@property (nonatomic, retain) NSNumber * until_id;
@property (nonatomic, retain) NSArray * topics;
@end

/////////////////////////////////////////////////////////////////////////

@class Login;

@interface Topic : NSObject {
    NSString * _name;
    Login * _creator;
    NSNumber * _message_count;
    NSNumber * _date_latest_message;
    NSNumber * _date_created;
    NSNumber * _tracked;
    NSNumber * _unread;
    NSNumber * _tid;
    NSString * _kind;
    NSNumber * _id;
}

@property (nonatomic, retain) NSString * name;
@property (nonatomic, retain) Login * creator;
@property (nonatomic, retain) NSNumber * message_count;
@property (nonatomic, retain) NSNumber * date_latest_message;
@property (nonatomic, retain) NSNumber * date_created;
@property (nonatomic, retain) NSNumber * tracked;
@property (nonatomic, retain) NSString * kind;
@property (nonatomic, retain) NSNumber * unread;
@property (nonatomic, retain) NSNumber * tid;
@property (nonatomic, retain) NSNumber * gid;
@property (nonatomic, readonly) NSString* topicNavURL;

@end

Now I am trying to access a particular topics name using:

RKObjectMapping* mapping = [RKObjectMapping mappingForClass:[TTTableTextItem class]];
 [mapping mapKeyPath:@"topics.name" toAttribute:@"text"];
 [mapping mapKeyPath:@"topics.topicNavURL" toAttribute:@"URL"];

However, this fails as it says that it doesn’t find name as topics is a NSArray. Is there a way to do KVC if I am dealing with array? Is it just NSString’s then?

Answer 1

Yes, you cannot access an array directly using KVC.
However you can use aggregates like @sum, @avg to calculate the sum, average

For ex: @sum.message_count will give you the total message count of all messages in the array. You don’t have to write any loop for that.