Swift / iOS 10：如何在应用程序中下载视频和存储

Question

我是SWIFT / Programming的新手，我无法在我的问题上找到答案，这就是为什么我要在这里尝试一下：

1. 我如何从URL下载视频（mp4）并将其存储在应用程序中**
2. 我如何在容器中显示视频**

我已经找到了这个话题：

Swift - Downloading video with downloadTaskWithURL

但就我而言，我不希望将视频保存在相机胶卷中。就在应用内。

感谢您的任何帮助/提示！

Answer 1

您可以使用URLSession的dataTask或downloadTask从url下载任何文件（如果可以下载）

以下是使用dataTask进行下载的方法：

    let videoUrl = "Some video url"

        let docsUrl = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!

    let destinationUrl = docsUrl.appendingPathComponent("MyFileSaveName")
    if(FileManager().fileExists(atPath: destinationUrl.path)){
            print("\n\nfile already exists\n\n")
        }
        else{
            //DispatchQueue.global(qos: .background).async {
                var request = URLRequest(url: URL(string: videoUrl)!)
                request.httpMethod = "GET"
                _ = session.dataTask(with: request, completionHandler: { (data, response, error) in
    if(error != nil){
        print("\n\nsome error occured\n\n")
        return
    }
    if let response = response as? HTTPURLResponse{
        if response.statusCode == 200{
            DispatchQueue.main.async {
                if let data = data{
                    if let _ = try? data.write(to: destinationUrl, options: Data.WritingOptions.atomic){
                        print("\n\nurl data written\n\n")
                    }
                    else{
                        print("\n\nerror again\n\n")
                    }
                }//end if let data
            }//end dispatch main
        }//end if let response.status
    }
}).resume()
            //}//end dispatch global
        }//end outer else

现在播放保存的文件：

class MyViewController: UIViewController {
 override func viewDidLoad() {
let baseUrl = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!

    let assetUrl = baseUrl.appendingPathComponent("MyFileSaveName")

    let url = assetUrl
    print(url)
    let avAssest = AVAsset(url: url)
    let playerItem = AVPlayerItem(asset: avAssest)


    let player = AVPlayer(playerItem: playerItem)

    let playerViewController = AVPlayerViewController()
    playerViewController.player = player

    self.present(playerViewController, animated: true, completion: {
        player.play()
    })
 }
}

但是，大多数站点不提供视频的直接dwonloadable链接。您可以通过在UIWebView中播放视频来获取该链接，并注册以下观察者以获取该链接：

NotificationCenter.default.addObserver(self, selector: #selector(videoPlayedInWebView), name: NSNotification.Name(rawValue: "AVPlayerItemBecameCurrentNotification"), object: nil)

 @objc func videoPlayedInWebView(aNotification: NSNotification) {
    if let playerItem: AVPlayerItem = aNotification.object as? AVPlayerItem{
        let asset: AVURLAsset = playerItem.asset as! AVURLAsset
        var downloadebaleVideoUrl = asset.url
        print(downloadebaleVideoUrl)
 }
}

这里“downloadebaleVideoUrl”是视频在webview中播放后生成的链接。如果您有任何问题随时问。注意：这仅适用于具有mp4文件的站点。使用此方法不会下载“HLS”流。为此您可以参考以下答案：https://stackoverflow.com/a/54493233/10758374

Answer 2

您需要创建一个本地URL，它将成为应用程序文件系统中的路径，并将视频数据写入其中。

    func writeToFile(urlString: String) {

    guard let videoUrl = URL(string: urlString) else {
        return
    }

    do {

        let videoData = try Data(contentsOf: videoUrl)

        let fm = FileManager.default

        guard let docUrl = fm.urls(for: .documentDirectory, in: .userDomainMask).first else {
            print("Unable to reach the documents folder")
            return false
        }

        let localUrl = docUrl.appendingPathComponent("test.mp4")

        try videoData.write(to: localUrl)

    } catch  {
        print("could not save data")
    }
 }

请记住始终在后台线程中调用此函数。