Swift　動画からフレーム分割した画像を生成したい

前提・実現したいこと

Swiftを使って読み込んだ動画から全フレームのキャプチャ画像を生成して表示させようとしているのですが，下記のコードでは1秒毎にしか画像を生成できません．
訂正すべき箇所等ご教授お願いいたします。

該当のソースコード

swift
1
2
3import UIKit
4import AVKit
5
6class ViewController: UIViewController, UIImagePickerControllerDelegate, UINavigationControllerDelegate {
7
8    var picker = UIImagePickerController()
9    var scrollView = UIScrollView()
10
11    override func viewDidLoad() {
12        super.viewDidLoad()
13
14        scrollView.frame = CGRect(x: 0, y: 0, width: view.frame.width, height: view.frame.height)
15        view.addSubview(scrollView)
16
17        // フォトライブラリーから動画を取得
18        picker.sourceType = UIImagePickerController.SourceType.photoLibrary
19        picker.mediaTypes = ["public.movie"]
20        picker.delegate = self
21        present(picker, animated: true, completion: nil)
22    }
23
24    func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [UIImagePickerController.InfoKey : Any]) {
25        dismiss(animated: true, completion: nil)
26
27        guard let videoURL = info[UIImagePickerController.InfoKey.mediaURL] as? URL else {
28            return
29        }
30
31        var images = [UIImage]()
32
33        let asset = AVAsset(url: videoURL)
34        let duration = CMTimeGetSeconds(asset.duration)
35        let generator = AVAssetImageGenerator(asset: asset)
36        generator.appliesPreferredTrackTransform = true
37        generator.requestedTimeToleranceAfter = CMTime.zero
38        generator.requestedTimeToleranceBefore = CMTime.zero
39        // 1秒毎にUIImageを生成
40        for index: Int in 0 ..< Int(duration) {
41            let floatTime = Float64(index)
42            let time = CMTimeMakeWithSeconds(floatTime, preferredTimescale: 600)
43            if let image = try? generator.copyCGImage(at: time, actualTime: nil) {
44		images.append(UIImage(cgImage: image))
45            }
46	}
47
48        // UIImageを画面に表示
49        var y: CGFloat = 0
50	let marginX: CGFloat = 50
51        let marginY: CGFloat = 10
52
53        for index: Int in 0 ..< images.count {
54
55            let image = images[index]
56            let width = view.frame.width - marginX*2
57            let ratio = width / image.size.width
58            let height = image.size.height * ratio
59
60            let imageView = UIImageView(image: image)
61            imageView.frame = CGRect(x: marginX, y: y, width: width, height: height)
62
63            scrollView.addSubview(imageView)
64            scrollView.contentSize = CGSize(width: view.frame.width, height: y + height)
65
66            y = y + height + marginY
67        }
68    }
69}
70
71