Does unifiedcontacts(matching:keystofetch:) return only unified contacts and leave out non-unified contacts?

See more:

iOS

Swift

When I use the Contacts Framework with Swift for iOS 15 using Xcode 13, when I use CNContactStore instance method unifiedContacts(matching:keysToFetch:), what happens to those CNContact objects that are not linked with any other CNContact objects, would they be returned as non-unified contacts, or would they be left out since they are non-unified contacts?

The sample iOS Swift project ManagingContacts, uses both enumerateContacts(with:usingBlock:) and unifiedContacts(withIdentifier:keysToFetch:). Understanding why they choose to use each when they do may help answer the question.

The name "unifiedContacts" suggests it only fetches unified contacts, and does not fetch non-unified contacts that otherwise would meet the specified criteria, but it doesn't make sense to me why there would ever be a need for it or why it is used in the said project when it is used.

What I have tried:

From my test code, it looks like they both do the same thing. What do you think about this?

I tried this code in a test project:

<pre lang="Swift">
class ViewController: UIViewController {
    let store = CNContactStore()
    
    let keys = [CNContactGivenNameKey as CNKeyDescriptor]
    
    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view.
        
        store.requestAccess(for: .contacts) {
            
            permissionGranted, error in
            
            let request = CNContactFetchRequest(keysToFetch: self.keys)
            
            print("enumerate contacts")
            
            do {
                
                try self.store.enumerateContacts(with: request) {
                    
                    contact, pointer in
                    
                    print(contact.givenName)
                    
                }
            
            } catch {
                
                print("error")
                print(error.localizedDescription)
                
            }
            
            print("unified contacts")
            
            do {
                
                let containers = try self.store.containers(matching: nil)
            
                if containers.count > 1 {
                    fatalError("More than one container!")
                }
                
                let predicate = CNContact.predicateForContactsInContainer(withIdentifier: self.store.defaultContainerIdentifier())
                
                let contacts = try self.store.unifiedContacts(matching: predicate, keysToFetch: self.keys)
                for contact in contacts {
                    
                    print(contact.givenName)
                    
                }
                
            } catch {
                
                print("error")
                print(error.localizedDescription)
            }
                        
        }
        
    }
}

Here's the result in the debug window:
enumerate contacts
Kate
Daniel
John
Anna
Hank
David
unified contacts
Kate
Daniel
John
Anna
Hank
David