Observe Boundary Timing

According to https://developer.apple.com/documentation/avfoundation/avplayer/1388027-addboundarytimeobserver I can observe to specified times that are traversed during playback.

func addBoundaryTimeObserver(forTimes times: [NSValue],queue: DispatchQueue?,using block: @escaping () -> Void) -> Any

And then there's example of how to detect times for each quarter of playback passed

func addBoundaryTimeObserver() {
    var times = [NSValue]()
    // Set initial time to zero
    var currentTime = kCMTimeZero
    // Divide the asset's duration into quarters.
    let interval = CMTimeMultiplyByFloat64(asset.duration, 0.25)
  
    // Build boundary times at 25%, 50%, 75%, 100%
    while currentTime < asset.duration {
        currentTime = currentTime + interval
        times.append(NSValue(time:currentTime))
    }
    // Queue on which to invoke the callback
    let mainQueue = DispatchQueue.main
    // Add time observer
     timeObserverToken = player.addBoundaryTimeObserver(forTimes: times,
                                                       queue: mainQueue) {
        // Update UI
    }

}

But how do I get which time from times array exactly was passed, so that I can know which quartile has passed?