How to create a Contact programmatically using swift 3 for iOS

createContact.swift

import Contacts

func createContact()->CNMutableContact{
        
        let contact = CNMutableContact()
        contact.namePrefix = "John"
        contact.nameSuffix = "Applesee"
        contact.organizationName = "Apple"
        contact.jobTitle = "Software Engineer"
        
        let dateFormatter = DateFormatter()
        dateFormatter.locale = Locale.current
        dateFormatter.dateStyle = DateFormatter.Style.medium
        let birthday = dateFormatter.date(from: "20/10/1995")
        
        let birthdayComponents = Calendar.current.dateComponents([.year, .month, .day], from: birthday!)
        contact.birthday = birthdayComponents
        
        let phone = CNLabeledValue(
            label:CNLabelPhoneNumberMain,
            value:CNPhoneNumber(stringValue:"555-5555"))
        
        let mobileNumber = CNLabeledValue(
            label:CNLabelPhoneNumberMobile,
            value:CNPhoneNumber(stringValue:"999-9999")
        
        contact.phoneNumbers = [phone, mobileNumber]
        
        let WorkEmail = CNLabeledValue(label:CNLabelWork, value: "john@apple.com")
        contact.emailAddresses = [WorkEmail]
        
        let address = CNMutablePostalAddress()
        address.street = "Infinity Loop"
        address.city = "Cupertino'
        address.state = "CA"
        address.postalCode = "95014"
        address.country = "United States"
        
        let labeledAddress = CNLabeledValue<CNPostalAddress>(label: CNLabelHome, value: address)
        
        contact.postalAddresses = [labeledAddress]
       
        return contact
}

The code above is great. I am using swift 4 and I had a tiny problem with the date. It gave an error when I run it saying unexpectedly found nil while unwrapping. I fixed it using dateFormatter.dateFormat = "dd-MM-yyyy". After adding this line the birthday property wasn't nil. I don't know if swift 3 or below would give the same problem.