Can not generate thumbnail from url video in ios 13 - swift

Question

I am using the below code to generate a frame from a video URL. This code was working fine for sometime before. right now it's not working. it is throwing an error that it can not decode and the file may be damaged. can someone help with this?
func previewImageFromVideo(url: NSURL) -> UIImage? {
let url = url as URL
let request = URLRequest(url: url)
let cache = URLCache.shared
if
let cachedResponse = cache.cachedResponse(for: request),
let image = UIImage(data: cachedResponse.data)
{
return image
}
let asset = AVAsset(url: url)
let imageGenerator = AVAssetImageGenerator(asset: asset)
imageGenerator.appliesPreferredTrackTransform = true
imageGenerator.maximumSize = CGSize(width: 250, height: 120)
var time = asset.duration
time.value = min(time.value, 2)
var image: UIImage?
do {
let cgImage = try imageGenerator.copyCGImage(at: time, actualTime: nil)
image = UIImage(cgImage: cgImage)
} catch { }
if
let image = image,
let data = UIImagePNGRepresentation(image),
let response = HTTPURLResponse(url: url, statusCode: 200, httpVersion: nil, headerFields: nil)
{
let cachedResponse = CachedURLResponse(response: response, data: data)
cache.storeCachedResponse(cachedResponse, for: request)
}
return image
}
This code throws an error while capturing a frame from the URL video. It says the file might be damaged.

Answer 1

I tried your code on Playground, it works perfectly. The file could be damaged as the error message says.
import UIKit
import AVKit
import PlaygroundSupport
let container = UIView(frame: CGRect(x: 0, y: 0, width: 200, height: 200))
let imageView = UIImageView(frame: CGRect(x: 0, y: 0, width: 200, height: 200))
container.addSubview(imageView)
PlaygroundPage.current.liveView = container
PlaygroundPage.current.needsIndefiniteExecution = true
func previewImageFromVideo(url: NSURL) -> UIImage? {
let url = url as URL
let request = URLRequest(url: url)
let cache = URLCache.shared
if
let cachedResponse = cache.cachedResponse(for: request),
let image = UIImage(data: cachedResponse.data)
{
return image
}
let asset = AVAsset(url: url)
let imageGenerator = AVAssetImageGenerator(asset: asset)
imageGenerator.appliesPreferredTrackTransform = true
imageGenerator.maximumSize = CGSize(width: 250, height: 120)
var time = asset.duration
time.value = min(time.value, 2)
var image: UIImage?
do {
let cgImage = try imageGenerator.copyCGImage(at: time, actualTime: nil)
image = UIImage(cgImage: cgImage)
} catch { }
if
let image = image,
let data = image.pngData(),
let response = HTTPURLResponse(url: url, statusCode: 200, httpVersion: nil, headerFields: nil)
{
let cachedResponse = CachedURLResponse(response: response, data: data)
cache.storeCachedResponse(cachedResponse, for: request)
}
return image
}
imageView.image = previewImageFromVideo(url: NSURL(string: "https://www.w3schools.com/html/mov_bbb.mp4")!)

Answer 2

I have made some changes to Suh's answer, and I have used it on the background thread so that while generating the thumbnail our UI won't get blocked.
func createVideoThumbnail( url: String?, completion: #escaping ((_ image: UIImage?)->Void)) {
guard let url = URL(string: url ?? "") else { return }
DispatchQueue.global().async {
let url = url as URL
let request = URLRequest(url: url)
let cache = URLCache.shared
if
let cachedResponse = cache.cachedResponse(for: request),
let image = UIImage(data: cachedResponse.data)
{
DispatchQueue.main.async {
completion(image)
}
}
let asset = AVAsset(url: url)
let imageGenerator = AVAssetImageGenerator(asset: asset)
imageGenerator.appliesPreferredTrackTransform = true
var time = asset.duration
time.value = min(time.value, 2)
var image: UIImage?
do {
let cgImage = try imageGenerator.copyCGImage(at: time, actualTime: nil)
image = UIImage(cgImage: cgImage)
} catch { DispatchQueue.main.async {
completion(nil)
} }
if
let image = image,
let data = image.pngData(),
let response = HTTPURLResponse(url: url, statusCode: 200, httpVersion: nil, headerFields: nil)
{
let cachedResponse = CachedURLResponse(response: response, data: data)
cache.storeCachedResponse(cachedResponse, for: request)
}
DispatchQueue.main.async {
completion(image)
}
}
}
Usage:
createVideoThumbnail(url: data.url ?? "") { [weak self] (img) in
guard let strongSelf = self else { return }
if let image = img {
strongSelf.mediaImg.image = image
}
}