My code doesn't return anything

import Foundation

struct Current {

    var currentTime: String?
    var temperature: Int
    var humidity: Double
    var precipProbability: Double
    var summary: String
    var icon: String

    init(weatherDictionary: NSDictionary) {
        let currentWeather = weatherDictionary["currently"] as NSDictionary

        temperature = currentWeather["temperature"] as Int
        humidity = currentWeather["humidity"] as Double
        precipProbability = currentWeather["precipProbability"] as Double
        summary = currentWeather["summary"] as String
        icon = currentWeather["icon"] as String

        let currentTimeIntValue = currentWeather["time"] as Int
        currentTime = dateStringFromUnixTime(currentTimeIntValue)
    }

    func dateStringFromUnixTime(unixTime: Int) -> String {
        let timeInSeconds = NSTimeInterval(unixTime)
        let weatherDate = NSDate(timeIntervalSince1970: timeInSeconds)

        let dateFormatter = NSDateFormatter()
        dateFormatter.timeStyle = .ShortStyle

        return dateFormatter.stringFromDate(weatherDate)
    }
}