如何将URL读取到AVURLAsset中

Question

我正在尝试创建一个类似于这样的AVURLAsset：

class TrimFootageViewController: UIViewController {
    var movieURL:URL?

    override func viewWillAppear(_ animated: Bool) {
        playerView.playerLayer.player = player

        super.viewWillAppear(animated)
        self.thumbnailImage = setThumbnailFrom(path: movieURL!)
        print(type(of: self.movieURL!))     
        asset = AVURLAsset(url: self.movieURL!, options: nil)
        print(asset ?? "couldn't get asset")

    }

这不能在另一个类上抛出错误(lldb)：线程1: EXC_BREAKPOINT (code=1，subcode=0x100318b4c)。此外，它不打印资产，所以我不相信它是正确的。

然而，当我使用：

class TrimFootageViewController: UIViewController {
        var movieURL:URL?

        override func viewWillAppear(_ animated: Bool) {
            playerView.playerLayer.player = player

            super.viewWillAppear(animated)
            self.thumbnailImage = setThumbnailFrom(path: movieURL!)
            print(type(of: self.movieURL!))  
            guard let movieURL = URL(string: "https://devimages-cdn.apple.com/samplecode/avfoundationMedia/AVFoundationQueuePlayer_HLS2/master.m3u8") else {
            return
             }   
            asset = AVURLAsset(url: movieURL, options: nil)
            print(asset ?? "couldn't get asset")

        }

它工作并正确地打印<AVURLAsset: 0x101b00210, URL = https://devimages-cdn.apple.com/samplecode/avfoundationMedia/AVFoundationQueuePlayer_HLS2/master.m3u8>。

self.movieURL！而movieURL在打印时都具有相同的URL类型。还请注意，在前面控制器的segue中，我是设置为self.movieURL的：

override func prepare(for segue: UIStoryboardSegue, sender: Any?){
        if segue.identifier == "TrimFootage_Segue" {
            let controller = segue.destination as! TrimFootageViewController
            controller.movieURL = self.videoRecorded
        }
    }

如何在movieURL调用中正确设置AVURLAsset资产，使其能够被实例化？

Answer 1

通过查看您的代码，似乎movieURL是filePath，因为setThumbnailFrom(path: movieURL!)运行良好。也许这就是原因。

通过应用if-let 检查as:，可以避免崩溃。

class TrimFootageViewController: UIViewController {
    var movieURL: URL?

    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)

        playerView.playerLayer.player = player   

        // Just check whether self.movieURL is filePath or URL
        // For "setThumbnailFrom" passing as file path
        // For "AVURLAsset(url: movURL, options: nil)" passing as URL

        self.thumbnailImage = setThumbnailFrom(path: self.movieURL!) // Passing as filePath 

        if let movURL = self.movieURL as? URL, let asset = AVURLAsset(url: movURL, options: nil) {
            print(asset)
        } else {
            print("Not able to load asset")
        }
    }
} 

确保您正在从前一个屏幕发送URL ：

let controller = segue.destination as! TrimFootageViewController
controller.movieURL = self.videoRecorded

Answer 2

1. 在TrimFootageViewController中，定义一个var movieURLString = ""。
2. 在前面的控制器的segue中:设置movieURLString而不是movieURL。
3. 然后，使用您的第二种方式init movieURL。

也许没问题。

Answer 3

我更新了你的密码。请看一下。它将不再崩溃，也请检查您是否正在从前一个控制器发送URL(不能为零)：

class TrimFootageViewController: UIViewController {
    var movieURL: URL?

    override func viewWillAppear(_ animated: Bool) {
        playerView.playerLayer.player = player

        super.viewWillAppear(animated)
        if let mURL = movieURL {
        self.thumbnailImage = setThumbnailFrom(path: mURL)
        print(type(of: mURL))     
        asset = AVURLAsset(url: mURL, options: nil)
        print(asset ?? "couldn't get asset")
        }    
    }