GPS track summary presenter with track ID

TrackSummaryPresenter.swift

protocol TrackSummaryPresenterOutput {
    func setTrackID(trackID: Int)
    func setName(name: String)
    func setDate(date: String)
    func setDistance(distance: String)
}

class TrackSummaryPresenter {
    let output: TrackSummaryPresenterOutput
    private let dateFormatter: NSDateFormatter

    init(output: TrackSummaryPresenterOutput) {
        self.output = output
        dateFormatter = NSDateFormatter()
        dateFormatter.dateStyle = .ShortStyle
    }
}

extension TrackSummaryPresenter: TrackSummaryInteractorOutput {
    func update(track: TrackSummary) {
        output.setTrackID(track.trackID)
        output.setName(track.name)
        output.setDate(stringForTime(track.startTime))
        output.setDistance(stringForDistance(track.distance))
    }

    private func stringForTime(time: Double) -> String {
        return dateFormatter.stringFromDate(NSDate(timeIntervalSince1970: time))
    }

    private func stringForDistance(distance: Float) -> String {
        return "\(distance) m"
    }
}