Swift 2.0 Format 1000's into a friendly K's

Question

I\'m trying to write a function to present thousands and millions into K\'s and M\'s For instance:

1000 = 1k
1100 = 1.1k
15000 = 15k
115000 = 115k
1000000 =          


        

Answer 1

To add to the answers, here's a Swift 4.X version of this using a loop to easily add/remove units if necessary:

extension Double {
    var shortStringRepresentation: String {
        if self.isNaN {
            return "NaN"
        }
        if self.isInfinite {
            return "\(self < 0.0 ? "-" : "+")Infinity"
        }
        let units = ["", "k", "M"]
        var interval = self
        var i = 0
        while i < units.count - 1 {
            if abs(interval) < 1000.0 {
                break
            }
            i += 1
            interval /= 1000.0
        }
        // + 2 to have one digit after the comma, + 1 to not have any.
        // Remove the * and the number of digits argument to display all the digits after the comma.
        return "\(String(format: "%0.*g", Int(log10(abs(interval))) + 2, interval))\(units[i])"
    }
}

Examples:

$ [1.5, 15, 1000, 1470, 1000000, 1530000, 1791200000].map { $0.shortStringRepresentation }
[String] = 7 values {
  [0] = "1.5"
  [1] = "15"
  [2] = "1k"
  [3] = "1.5k"
  [4] = "1M"
  [5] = "1.5M"
  [6] = "1791.2M"
}