如何将 URL 读入 AVURLAsset

Question

我正在尝试创建一个AVURLAsset，如下所示：

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")
    }

这在另一个类上抛出错误 (lldb( 不起作用：线程 1：EXC_BREAKPOINT(代码 = 1，子代码 = 0x100318b4c(。此外，它不会打印资产，因此我认为它设置不正确。

但是当我使用时：

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")
        }

它可以正常工作并正确打印<AVURLAsset: 0x101b00210, URL = https://devimages-cdn.apple.com/samplecode/avfoundationMedia/AVFoundationQueuePlayer_HLS2/master.m3u8>

self.movieURL！和movieURL在打印时都具有相同类型的URL。另请注意，我在以前的控制器的 segue 中像这样设置 self.movieURL：

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 AVURLAsset 调用中正确设置 movieURL 资产，以便可以实例化它？

Answer 1

通过查看您的代码，似乎movieURL是 filePath，因为setThumbnailFrom(path: movieURL!)工作正常。也许这可能是原因。

您可以通过应用if-let检查来避免崩溃：

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")
        }
    }
} 

确保您从上一个屏幕发送URL：

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

Answer 2

1. 在TrimFootageViewController 中，定义一个var movieURLString = ""。
2. 在上一个控制器的 segue 中：设置movieURLString而不是movieURL。
3. 然后，使用第二种方式初始化movieURL。

也许还可以。

Answer 3

我已经更新了你的代码。请看一看。它不会再崩溃了，还请检查您是否正在从以前的控制器发送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")
        }    
    }