Restkit: Nested relationship mapping - ios

Question

I have the following JSON:
{
"votecategory": [
{
"id": "nlvfl2",
"title": "Best Song",
"pollQuestion": {
"id": "nbprqp",
"title": "best-song",
"displayText": "Best Song",
"answer": [
{
"id": "qylaw4",
"title": "Bruno Mars – Locked Out Of Heaven",
"relatedItems": [
{
"Name": "Bruno Mars",
"id": "sljkur",
"Bio": "Bio info here"
},
{} //Sometimes there's an empty object
],
"winner": "true"
},
{
"id": "q05sb3",
"title": "Daft Punk – Get Lucky (ft. Pharrell Williams)",
"displayText": "Daft Punk – Get Lucky (ft. Pharrell Williams)",
"relatedItems": [
{
"Name": "Daft Punk",
"id": "d9sd84",
"Bio": "Bio info here"
}
]
},
...
]
}
},
...
]
}
Which maps to the following entities:
Category (votecategory values)
Nomination (answer values)
Artist (relatiedItems values)
Ive managed to setup object and relationship mappings for votecategory (category) -> answer (nomination), however I'm having a problem mapping nomination to artist.
What I need to do is have a 1:1 core data relationship setup between nomination and artist, and 1:N relationship setup between artists and nomination (one artist can have multiple nominations).
The problem is that "relatedItems" is an array, but in reality only contains 1 usable value, the related artist. This "should" be a 1:1 relationship from a data perspective, however the JSON maps it as a 1:N relationship, this confuses restkit (rightfully so).
How can I store the single item in the JSON relatedItems response as a single 1:1 relationship?
Thanks
Oli

Answer 1

You could look at using a custom value transformer on that mapping which converts the array into a single object. Check out this question for some additional details.