如何查看地址簿的联系人是否有姓名？

Question

我在Swift中创建了一个应用程序，当我尝试获取addressBook的联系人时检查是否有电子邮件，但是当我尝试检查是否有名称时，我收到错误

  func peoplePickerNavigationController(peoplePicker: ABPeoplePickerNavigationController!, shouldContinueAfterSelectingPerson person: ABRecordRef!) -> String {
    let emails: ABMultiValueRef = ABRecordCopyValue(person, kABPersonEmailProperty).takeUnretainedValue()

    if (ABMultiValueGetCount(emails) > 0) { //here check if have email

 let name: ABMultiValueRef = ABRecordCopyValue(person, kABPersonFirstNameProperty).takeUnretainedValue()
        if(ABMultiValueGetCount(name)!=nil){//Here try check if have name, but this is incorrect form to do this ...

如何检查这是否有姓名或姓氏？

谢谢！