A Live Photo is a paired camera photo ("key photo") and video recording ("paired video"). Learn more about Live Photos from our in-depth blog post.

A Live Photo consists of two resources paired using an asset identifier (a UUID string):

1. JPEG image with special metadata for kCGImagePropertyMakerAppleDictionary with [17 : assetIdentifier]
2. Quicktime MOV with
   1. Quicktime metadata for ["com.apple.quicktime.content.identifier" : assetIdentifier]
   2. Timed metadata track with ["com.apple.quicktime.still-image-time" : 0xFF]. This lets the system know where the still image sits in the movie timeline.

The entire library is contained in the LivePhoto.swift file:

LivePhoto.extractResources(from: livePhoto, completion: resources -> Void) {
  let pairedImageURL = resources.pairedImageURL
  let pairedVideoURL = resources.pairedVideoURL
}

LivePhoto.generate(from: photoURL, videoURL: videoURL, progress: { percent in }, completion: { livePhoto, resources in
  // Display the Live Photo in a PHLivePhotoView
  livePhotoView.livePhoto = livePhoto
  // Or save the resources to the Photo library
  LivePhoto.saveToLibrary(resources)
  })