Use case for presenting GPS track summary

TrackSummaryInteractor.swift

protocol TrackSummaryInteractorOutput {
    func update(track: TrackSummary)
}

class TrackSummaryInteractor {
    let output: TrackSummaryInteractorOutput

    init(output: TrackSummaryInteractorOutput) {
        self.output = output
    }

    func execute() {
        //
        // Implement business logic for getting track details.
        //
        output.update(TrackSummary(name: "Track", startTime: 1234567890, distance: 100))
    }
}