Calculate age from birth date using textfield and NSDateComponents in Swift4 - swift

Question

I am trying calculate the age from birthday Date in Swift with this function: (want to write in a textField and pass this data from VC in a Label)
{
var a = self.dob.text
var c = a!.components(separatedBy: "-")
var y1 = c[2]
let cal = NSCalendar? = NSCalendar(calendarIdentifier: .gregorian)
let now = Date()
let year = Calendar.components(.year, from: dob!, to: now, options: [])
let age = (year!) - Int(y1)!
self.myage.text = String(age)
}
But I get an error cannot assign NSCalendar?.Type, but I don't know why get this error (its my first time coding)

Answer 1

You have a few problems in your code. First there is a type as already mentioned by Qi Hao, second you are passing dob is a text field you and Calendar components method expects two dates, so you should first parse the text field date then you can get the year component difference from input date and now:
Playground Testing
let dob = UITextField()
dob.text = "03-27-2002"
let dateFormatter = DateFormatter()
dateFormatter.locale = Locale(identifier: "en_US_POSIX")
dateFormatter.dateFormat = "MM-dd-yyyy"
if let date = dateFormatter.date(from: dob.text!) {
let age = Calendar.current.dateComponents([.year], from: date, to: Date()).year!
print(age) // 16
}

Answer 2

func age(on baseDate: DateComponents) -> Int {
if baseDate.month > month {
return baseDate.year - year
}
if baseDate.month == month && baseDate.day >= day {
return baseDate.year - year
}
return baseDate.year - year - 1
}

Answer 3

try this:
func calcAge(birthday: String) -> Int {
let dateFormater = DateFormatter()
dateFormater.dateFormat = "MM/dd/yyyy"
let birthdayDate = dateFormater.date(from: birthday)
let calendar: NSCalendar! = NSCalendar(calendarIdentifier: .gregorian)
let now = Date()
let calcAge = calendar.components(.year, from: birthdayDate!, to: now, options: [])
let age = calcAge.year
return age!
}