Assigning NSDateComponents to a label - swift

Question

I'm creating a mobile app that has a countdown to a specific date. I think I have the timer itself correct, but I'm struggling to get it into a format where I can assign it to my label. I'm getting an error "Cannot invoke initializer for type 'String' with an argument list of type '(NSDateComponents)'. This error is found at the line "var date = String(openingGavelDate)". The outlet for the label has been properly created in this file.
First step I took was creating the date variable and setting it equal to the converted value of my other variable. Second step involved trying to look through documentation but so far I haven't really found any substantial documentation that can help.
func createGavelTimer() {
let openingGavelDate = NSDateComponents()
openingGavelDate.year = 2019
openingGavelDate.month = 7
openingGavelDate.day = 16
openingGavelDate.hour = 14
openingGavelDate.minute = 00
openingGavelDate.timeZone = NSTimeZone(abbreviation: "CST")! as TimeZone
var date = String(openingGavelDate) //problem is here
countdownLabel.text = date
}

Answer 1

One of possible solutions:
let date = Calendar.current.date(from: openingGavelDate)
let dateFormatter = DateFormatter()
dateFormatter.timeStyle = .short
dateFormatter.dateStyle = .medium
dateFormatter.doesRelativeDateFormatting = true
dateFormatter.timeZone = TimeZone(abbreviation: "CST")!
let yourString = dateFormatter.string(from: date)

Answer 2

Try converting the NSDateComponents object to a Date by using Calendar.date(from:), and then converting that to a String using a DateFormatter:
let gregorianCalendar = Calendar(identifier: .gregorian)
if let date = gregorianCalendar.date(from: openingGavelDate as DateComponents) {
let dateFormatter = DateFormatter()
dateFormatter.dateStyle = .medium
dateFormatter.timeStyle = .none
countdownLabel.text = dateFormatter.string(from: date)
}
Also, as #Sh_Khan and #rmaddy have commented, you should be using DateComponents, TimeZone, etc. instead of their NS counterparts (unless you're using Swift 2 or lower).

Answer 3

Two things you need to do to form your date:
Set a calendar on the DateComponents instance.
Get your date by accessing the date property on your DateComponents instance.
Also, I'd recommend using time zone identifiers instead of abbreviation to specify a time zone; advantage is that identifiers will automatically apply special rules such as daylight savings as appropriate. (Below I've substituted the "America/Chicago" zone for UTC.)
Try this code in a playground:
var openingGavelDate = DateComponents()
let timeZone = TimeZone(identifier: "America/Chicago")!
openingGavelDate.year = 2019
openingGavelDate.month = 7
openingGavelDate.day = 16
openingGavelDate.hour = 14
openingGavelDate.minute = 00
openingGavelDate.calendar = Calendar.current
openingGavelDate.timeZone = timeZone
let date = openingGavelDate.date
print(date ?? "no date")
Output: 2019-07-16 19:00:00 +0000 (your date in GMT.)
This will get you a date, but notice that the Date class prints in GMT by default, because Date has no concept of timezone.
To print date in the timezone and format you want, use DateFormatter:
let f = DateFormatter()
f.dateFormat = "yyyy-MM-dd hh:mm a"
f.timeZone = TimeZone(identifier: "America/Chicago")!
print(f.string(from: date!))
Output: 2019-07-16 02:00 PM (your date & time, in CST and formatted for reading.)
DateFormatter allows you to either control the format yourself, or follow the user's system settings to determine what is in the final string. See the docs for DateFormatter to see how to get it into the format you want to display.