Export HDR media in your app with AVFoundation

// AVAssetExportSession code snippet

guard let exportSession = AVAssetExportSession(asset: sourceAsset,
                      presetName: AVAssetExportPresetHEVCHighestQuality) else {
	// Handle error
}

exportSession.outputURL = outputURL 
exportSession.outputFileType = AVFileTypeQuickTimeMovie 

exportSession.exportAsynchronouslyWithCompletionHandler {
	// Handle completion 
}

// AVAssetWriter with sourceFormatHint

let assetWriter = try AVAssetWriter(url: outputURL, fileType: AVFileTypeQuickTimeMovie)

let outputSettings: [String: AnyObject] = [
			AVVideoCodecKey: AVVideoCodecTypeHEVC
		]

let assetWriterInput = AVAssetWriterInput(mediaType: AVMediaTypeVideo,
                                     outputSettings: outputSettings
                                   sourceFormatHint: videoFormatDescription)

assetWriter.add(assetWriterInput)

guard assetWriter.startWriting() else {
	throw assetWriter.error!
}

// AVAssetWriter with AVOutputSettingsAssistant

let assetWriter = try AVAssetWriter(url: outputURL, fileType: AVFileTypeQuickTimeMovie)

let settingsAssistant = AVOutputSettingsAssistant(
                                     preset: AVOutputSettingsPreset.hevc1920x1080)

settingsAssistant.sourceVideoFormat = videoFormatDescription

let newVideoSettings = settingsAssistant.videoSettings

// Modify a few fields in newVideoSettings here

let assetWriterInput = AVAssetWriterInput(mediaType: AVMediaTypeVideo,
                                     outputSettings: newVideoSettings)

assetWriter.add(assetWriterInput)
guard assetWriter.startWriting() else {
	throw assetWriter.error!
}