TimeIntervalFormatter

The missing TimeIntervalFormatter for TimeInterval.

Example

let formatter = TimeIntervalFormatter()

formatter.style = .mmssf
formatter.fractionDigits = 2
formatter.fractionSeparator = "´"

let interval = TimeInterval(123.45)
formatter.string(from: interval) // "02:03´45"

interval == formatter.timeInterval(from: "02:03´45") // true