ios - Swift - Get date from day of year

Question

We can get day of year for date using below line.

let day = cal.ordinalityOfUnit(.Day, inUnit: .Year, forDate: date)

But how can we get the date from day of year?

Answer 1

If you know the year you can get DateComponents date property as follow:

extension Calendar {
    static let iso8601 = Calendar(identifier: .iso8601)
}


let now = Date()
let day  = Calendar.iso8601.ordinality(of: .day, in: .year, for: now)!  // 121
let year = Calendar.iso8601.component(.year, from: now)  // 2017
let date = DateComponents(calendar: .iso8601, year: year, day: day).date   //  "May 1, 2017, 12:00 AM"

or using DateFormatter

let dateFormatter = DateFormatter()
dateFormatter.dateFormat = "yyyy D"
if let date = dateFormatter.date(from: "(year) (day)") {
    dateFormatter.dateStyle = .medium
    dateFormatter.timeStyle = .short
    dateFormatter.string(from: date)    // "May 1, 2017, 12:00 AM"
}