ios - 使用 Swift 3 获取所有没有关联名称的联系人

Question

我想获取所有存储的没有名字的联系人。下面的方法帮助我搜索所有传递字符串的联系人。我试图传递空字符串来查找所有没有名字的联系人，但没有成功。

func fetchContactsWithNoName() {

    let contactStore = CNContactStore()
    // Get all the containers
    var allContainers: [CNContainer] = []
    do {
        allContainers = try contactStore.containers(matching: nil)
    } catch {
        print("Error fetching containers")
    }

    // Iterate all containers and append their contacts to our results array
    for _ in allContainers {
      //  let fetchPredicate = CNContact.predicateForContactsInContainer(withIdentifier: container.identifier)

        do {
            let containerResults =  try contactStore.unifiedContacts(matching: CNContact.predicateForContacts(matchingName: " "), keysToFetch:[CNContactGivenNameKey as CNKeyDescriptor, CNContactFamilyNameKey as CNKeyDescriptor])
            self.results.append(contentsOf: containerResults)

        } catch {
            print("Error fetching results for container")
        }
    }

}