VideoCompression.swift

//
//  ViewController.swift
//  VideoCompression
//
//  Created by Gabriel Lima on 02/03/19.
//  Copyright © 2019 Gabriel Lima. All rights reserved.
//

import UIKit
import AVFoundation
import NextLevelSessionExporter

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        
        imagePicker()
    }
    
    func imagePicker() {
        let imagePickerController = UIImagePickerController()
        imagePickerController.delegate = self
        imagePickerController.sourceType = .photoLibrary
        imagePickerController.mediaTypes = ["public.image", "public.movie"]
        imagePickerController.videoExportPreset = AVAssetExportPresetPassthrough
        
        present(imagePickerController, animated: true, completion: nil)
    }
}

extension ViewController: UIImagePickerControllerDelegate, UINavigationControllerDelegate {
    
    func imagePickerController(_ picker: UIImagePickerController,
                               didFinishPickingMediaWithInfo info: [UIImagePickerController.InfoKey : Any]) {
        
        let videoUrl = info[UIImagePickerController.InfoKey.mediaURL] as! URL
        
        let tmpDirectory = URL(fileURLWithPath: NSTemporaryDirectory(), isDirectory: true)
            .appendingPathComponent(ProcessInfo().globallyUniqueString)
            .appendingPathExtension("MOV")
        
        let asset = AVAsset(url: videoUrl)
        
        let exporter = NextLevelSessionExporter(withAsset: asset)
        
        exporter.outputURL = tmpDirectory
        
        let compressionDict: [String: Any] = [
            AVVideoAverageBitRateKey: NSNumber(integerLiteral: 1_000_000),
            AVVideoProfileLevelKey: AVVideoProfileLevelH264HighAutoLevel as String,
        ]
        
        let videoOutputConfig: [String: Any] = [
            AVVideoCodecKey: AVVideoCodecType.h264,
            AVVideoWidthKey: NSNumber(integerLiteral: 1280),
            AVVideoHeightKey: NSNumber(integerLiteral: 720),
            AVVideoScalingModeKey: AVVideoScalingModeResizeAspectFill,
            AVVideoCompressionPropertiesKey: compressionDict
        ]
        
        let audioOutputConfig: [String: Any] = [
            AVFormatIDKey: kAudioFormatMPEG4AAC,
            AVEncoderBitRateKey: NSNumber(integerLiteral: 128000),
            AVNumberOfChannelsKey: NSNumber(integerLiteral: 2),
            AVSampleRateKey: NSNumber(value: Float(44100))
        ]
        
        asset.nextlevel_export(outputURL: tmpDirectory, videoOutputConfiguration: videoOutputConfig, audioOutputConfiguration: audioOutputConfig)
        
        dismiss(animated: true, completion: nil)
    }
}

extension URL {
    var attributes: [FileAttributeKey : Any]? {
        do {
            return try FileManager.default.attributesOfItem(atPath: path)
        } catch let error as NSError {
            print("FileAttribute error: \(error)")
        }
        return nil
    }
    
    var fileSize: UInt64 {
        return attributes?[.size] as? UInt64 ?? UInt64(0)
    }
    
    var fileSizeString: String {
        return ByteCountFormatter.string(fromByteCount: Int64(fileSize), countStyle: .file)
    }
    
    var creationDate: Date? {
        return attributes?[.creationDate] as? Date
    }
}