Haptic Video Sync (UIKit + SwiftUI)

Play an HLS or local video in lockstep with an Apple Core Haptics .ahap pattern — all with the native AVPlayerViewController controls (play/pause/seek/scrub). Includes a SwiftUI grid to launch multiple clips and simple CLI tools to convert a TSV/CSV timeline into AHAP.

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🎥 Watch the video: How I figured it out

I walk through working out how apple made there haptic F1 trailer

▶️ Watch here: https://youtu.be/g6TUiQzcwac

🎥 Watch the video: How I built this haptic player

I walk through the entire approach — parsing .ahap, syncing to AVPlayer, drift correction, and edge cases.

▶️ Watch here: https://youtu.be/MguJGtUWqa0

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Features

• ✅ Uses AVPlayerViewController’s built-in UI (no custom buttons)
• ✅ Syncs haptics on Play / Pause / Seek / Scrub / Time Jump / Stall / End
• ✅ Light periodic re-pin (defaults to ~300ms) to prevent drift
• ✅ Works with remote and bundled .ahap files
• ✅ SwiftUI grid to browse and launch clips
• ✅ Simple TSV/CSV → AHAP converters (PHP or Bash+awk+jq)

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Requirements

• iOS 14+ (iOS 15+ recommended)
• Real device (Simulator doesn’t do Core Haptics)
• Settings → Sounds & Haptics → System Haptics = ON
• HTTPS access for remote HLS/AHAP

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How it works (high level)

• Clock of truth: AVPlayer time
• Haptics: CHHapticEngine + CHHapticAdvancedPatternPlayer
• Sync strategy:
  • Mirror player state with:
    • player.timeControlStatus (play/pause/waiting)
    • AVPlayerItemTimeJumped, AVPlayerItemPlaybackStalled, AVPlayerItemDidPlayToEndTime
  • On each event: seek the haptics to player.currentTime() and start/resume/pause to match
  • During playback: periodically re-pin haptics to the video time (tiny nudge, drift-free)

There’s no public haptic currentTime. We don’t read a haptic playhead; we slave haptics to video time instead.

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AHAP quickstart

An .ahap is JSON with Version and a Pattern array of events/curves. Example:

{
  "Version": 1,
  "Pattern": [
    {
      "Event": {
        "EventType": "HapticContinuous",
        "Time": 2.0,
        "EventDuration": 1.0,
        "EventParameters": [
          { "ParameterID": "HapticIntensity", "ParameterValue": 0.6 },
          { "ParameterID": "HapticSharpness", "ParameterValue": 0.3 }
        ]
      }
    },
    {
      "ParameterCurve": {
        "ParameterID": "HapticIntensity",
        "Time": 2.0,
        "ParameterCurveControlPoints": [
          { "Time": 2.0, "ParameterValue": 0.2 },
          { "Time": 3.0, "ParameterValue": 0.9 }
        ]
      }
    }
  ]
}

HapticTransient = tap HapticContinuous + EventDuration = rumble All times in seconds; intensity/sharpness in 0…1.

File Creation.

I created the Haptic file in something called CuePoint, its not build for this but worked really well. I wrote some php to convert my output .txt to the needed json structure. Your millage may be different.

More info is needed here but it is a baseline, hope you enjoy.

Thomas Dye