Set Table Section Titles from Realm Query - ios

Question

I've searched for the answer to this (I'm sure it's there somewhere) but can't find it.
I am trying to populate a UITableView's section headers from a Realm database, where the section title is in a related class.
My Realm classes:
class Person: Object {
#objc dynamic var personId = UUID().uuidString
#objc dynamic var firstName: String = ""
#objc dynamic var surname: String = ""
#objc dynamic var mobileNumber: Int = 0
#objc dynamic var password: String = ""
override static func primaryKey() -> String? {
return "personId"
}
}
class Group: Object {
#objc dynamic var groupId = UUID().uuidString
#objc dynamic var person: Person?
#objc dynamic var groupName: String = ""
let groupContent = List<String>()
override static func primaryKey() -> String? {
return "groupId"
}
}
I want to retrieve the groupName results for the current user and use them as table section headers. The number of groupNames is dynamic for each user.
My current code, which doesn't work at all is:
func getGroupNames() {
let mobileNumber = UserDefaults.standard.integer(forKey: "mobileNumber")
let personResult = realm.objects(Person.self).filter("mobileNumber == %#", mobileNumber)
let groupNames = realm.objects(Group.self).filter("person == %#", personResult.self.first)
return (groupNames)
}
I can't get groupNames to be useful as section headers.
Help will be appreciated!
Thanks.
UPDATE
I now have:
func getGroupNames() -> [String] {
let mobileNumberInt = mobileNumber
let groupNames = realm.objects(Group.self).filter("person.mobileNumber == %#", mobileNumberInt).map({$0.groupName})
return Array(groupNames)
}
This returns ["Group Name 1", "Group Name 2"] twice (no matter how many objects are in the results). Why twice, and now how do I get these into my section headers? I've tried:
func tableView(_ tableView: UITableView, titleForHeaderInSection section: Int) -> [String] {
return getGroupNames()
}
The quantity of sections works, but the headers are not showing.

Answer 1

Assuming you already know the mobile number of a person, you can use following code to fetch groups a person belongs to.
func getGroupNames() -> [Group]? {
let realm = try Realm()
let mobileNumber = UserDefaults.standard.integer(forKey: "mobileNumber")
let groupNames = realm.objects(Group.self).filter("person.mobileNumber == %#", mobileNumber)
return Array(groupNames)
}