Enables smooth frame-by-frame scrubbing (in both directions) – similar to Apple's applications.

AVPlayer+Scrubbing.swift

public enum Direction {
    case forward
    case backward
}

internal var player: AVPlayer?

private var isSeekInProgress = false
private var chaseTime = kCMTimeZero
private var preferredFrameRate: Float = 23.98

public func seek(to time: CMTime) {
    seekSmoothlyToTime(newChaseTime: time)
}

public func stepByFrame(in direction: Direction) {
    let frameRate = preferredFrameRate
        ?? player?.currentItem?.tracks
            .first(where: { $0.assetTrack.mediaType == .video })?
            .currentVideoFrameRate
        ?? -1

    let time = player?.currentItem?.currentTime() ?? kCMTimeZero
    let seconds = Double(1) / Double(frameRate)
    let timescale = Double(seconds) / Double(time.timescale) < 1 ? 600 : time.timescale
    let oneFrame = CMTime(seconds: seconds, preferredTimescale: timescale)
    let next = direction == .forward
        ? CMTimeAdd(time, oneFrame)
        : CMTimeSubtract(time, oneFrame)

    seekSmoothlyToTime(newChaseTime: next)
}

private func seekSmoothlyToTime(newChaseTime: CMTime) {
    if CMTimeCompare(newChaseTime, chaseTime) != 0 {
        chaseTime = newChaseTime

        if !isSeekInProgress {
            trySeekToChaseTime()
        }
    }
}

private func trySeekToChaseTime() {
    guard player?.status == .readyToPlay else { return }
    actuallySeekToTime()
}

private func actuallySeekToTime() {
    isSeekInProgress = true
    let seekTimeInProgress = chaseTime

    player?.seek(to: seekTimeInProgress, toleranceBefore: kCMTimeZero, toleranceAfter: kCMTimeZero) { [weak self] _ in
        guard let `self` = self else { return }

        if CMTimeCompare(seekTimeInProgress, self.chaseTime) == 0 {
            self.isSeekInProgress = false
        } else {
            self.trySeekToChaseTime()
        }
    }
}

https://stackoverflow.com/a/17331242/2742007

avPlayer.currentItem?.step(byCount: isForward ? 1 : -1)

https://developer.apple.com/documentation/avfoundation/avplayeritem/1387968-step

https://stackoverflow.com/a/17331242/2742007

avPlayer.currentItem?.step(byCount: isForward ? 1 : -1)

https://developer.apple.com/documentation/avfoundation/avplayeritem/1387968-step

This is not relevant I'm afraid. Or more importantly it's incomplete. If you read (or even try) that API out yourself, you'll note that it's not performant in most user-driven cases and cannot chase smoothly. This is because it doesn't cancel previous seeks.

The provided example solves this problem for high performance cases. The API you're suggesting is fine for non-interactive scenarios though 👍