Coredata update/insert for one to many relationship - swift

Question

I have a one to many relationship in my coredata object graph, typically User<->>Device. Lets say from my API i get a response of something as bellow
[
{
user:"John"
id:1
devices:[
{
id:1
name:"iPhoneX"
},
{
id:2
name:"Samsung Galaxy Plus"
}
]
},
{
user:"Peter"
id:"2"
devices:[
{
id:3
name:"iPhone5s"
},
{
id:4
name:"Samsung Galaxy"
}
]
}
]
Now the objective is to do a simple update/insert to my coredata tables. My Partial code as bellow for updating and inserting Device table
func updateDevice (userID:String, apiDevicesArray:[APIResposeDevice]){
for device in apiDevicesArray {
let request:NSFetchRequest<Device> = Device.fetchRequest()
request.predicate = NSPredicate(format:"id = %#", device.id)
do{
let searchResults = try self.privateMOC.fetch(request)
if searchResults.count > 0 {
//Update
let update_device = searchResults.last
update_device.name = device.name
update_device.id = device.id
}else{
//Stuck with inserting a device to the proper user
request.predicate = NSPredicate(format: "owner.id = %#, userID)
do{
let devicesArrayForUserID = try self.privateMOC.fetch(request)
//How to insert a record to this array now ???
}catch{
}
}
}catch{
}
}
}

Answer 1

First, you need to fetch the User.
Then, you have to choices:
user.devices.add(device)
or if it's two ways relationship, then you can call device.user = user