Coredata toMany relationship mapping issue - Swift - swift

Question

I have two tables Category and Sub Category.
Category has toMany Relationship with SubCategory.
SubCategory has toMany Relationship with SubCategory. (SubCategory may have subcategories)
DB Model:
Json Response
{
"response": {
"status": true,
"message": "Category listed",
"code": 200
},
"data": [
{
"description": "Memory Questions",
"id": "QT05",
"title": "Memory",
"subcategory": [
{
"title": "Patterns",
"id": "QT05P",
"subcategory": [
{
"title": "Squares",
"id": "QT05PS",
"demo": {
"type": "image",
"value": "Memory/images/demo_QT05PS.png"
}
},
{
"title": "Circles",
"id": "QT05PC",
"demo": {
"type": "image",
"value": "Memory/images/demo_QT05PC.png"
}
},
{
"title": "Triangles",
"id": "QT05PT",
"demo": {
"type": "image",
"value": "Memory/images/demo_QT05PT.png"
}
},
{
"title": "Rectangles",
"id": "QT05PR",
"demo": {
"type": "image",
"value": "Memory/images/demo_QT05PR.png"
}
}
],
"demo": {
"type": "image",
"value": "Memory/images/demo_QT05P.png"
}
}
]
}
]
}
Sub Category Model Class (CoreData)
extension SubCategory{
func addSubCategory(subcategory:SubCategory) {
var sub = self.mutableSetValueForKey("subcategories")
sub.addObject(subcategory)
}
func setSubCategories(subCategories:NSArray){
var sub = self.mutableSetValueForKey("subcategories")
for subcategory in subCategories {
sub.addObject(subcategory)
}
}
}
Mapping JSON
func mapCategory(dict:NSDictionary?) -> LUBaseResponse? {
if (dict == nil) {
return nil
}
var response = self.mapStatus(dict!)
if (response != nil){
if (response!.status == 1){
let data:NSArray = dict!["data"] as NSArray
var categoryArray = NSMutableArray()
for categoryDict in data {
if (self.fetchCategory(categoryDict["id"] as? String) == nil){
var category = NSEntityDescription.insertNewObjectForEntityForName("Category", inManagedObjectContext: self.managedObjectContext!) as? Category
category?.categoryDescription = categoryDict["description"] as String
category?.categoryId = categoryDict["id"] as String
category?.categoryTitle = categoryDict["title"] as String
var subcategory = self.mapSubcategory(categoryDict["subcategory"] as? NSArray,category: category!)
if (subcategory != nil && subcategory?.count > 0){
category?.setSubCategories(subcategory!)
}
categoryArray.addObject(category!)
}
LUCoreData.sharedInstance.saveContext()
}
response?.data = categoryArray
}
}
return response
}
//Issue in this method
private func mapSubcategory(array:NSArray?,category:Category) -> NSMutableArray? {
var subcategoriesObjects = NSMutableArray()
if (array?.count > 0){
var subcategories = array!
NSEntityDescription.insertNewObjectForEntityForName("SubCategory", inManagedObjectContext: self.managedObjectContext!) as? SubCategory
for subcategoryDict in subcategories {
var title = subcategoryDict["title"]
if (self.fetchSubCategory(subcategoryDict["id"] as? String) == nil) {
var subcategory = NSEntityDescription.insertNewObjectForEntityForName("SubCategory", inManagedObjectContext: self.managedObjectContext!) as? SubCategory
subcategory?.title = subcategoryDict["title"] as String
subcategory?.id = subcategoryDict["id"] as String
subcategory?.categoryOf = category
var arraySubCategory = subcategoryDict.objectForKey("subcategory") as? NSArray
if (arraySubCategory?.count > 0){
var nestedSubCategory = self.mapSubcategory(arraySubCategory,category: category)
if (nestedSubCategory != nil){
var sub = nestedSubCategory!.objectAtIndex(0) as SubCategory
println("Sub is \(sub.subcategories)") //Returns Empty
subcategory!.setSubCategories(nestedSubCategory!)
//Issue Here
println("Sub is \(sub.subcategories)")
}
}
subcategoriesObjects.addObject(subcategory!)
}
LUCoreData.sharedInstance.saveContext()
}
}
return subcategoriesObjects
}
Problem:
In JSON Response, you can see that Memory(Category) has subcategories "Patterns", which has nested SubCategories "Square","Circles" etc.
This looping is executed in "mapSubcategory" function
After this line "subcategory!.setSubCategories(nestedSubCategory!)"
In the above images, you can see that when nested subcategory("Squares" which has no further subcategories) added to parent subcategory, the parent subcategory(patterns) is added to Square as subcategory. This cause recursive (Parent -> Child -> Parent -> Child ....). I am not sure how it is recursively adding parent to child.

Answer 1

I have fixed this by removing inverse relationship from subcategory table.