如何将UIImage保存到文档目录？

Question

如何将UIImage保存到文档目录？

iosswiftavfoundationpersistencefile-manager

9

我正试图将一个录制视频的文件路径和缩略图保存到文档目录中。然后，使用这些文件路径将这两个值设置为一个对象，以便我可以使用该对象来填充集合视图。使用我当前的代码（如下），在我录制视频后，视频路径被保存到文档目录中，并且视频路径和缩略图被设置到我的Post对象中，缩略图在我的集合视图中正常显示。

然而，由于只有视频路径位于目录中，因此仅视频路径会在应用程序重新启动后保持不变，而缩略图并不会。我想把缩略图也保存在那里，但是我不知道怎样做，因为似乎只能将URL写入目录中。

这是我第一次使用文档目录，所以任何帮助都将不胜感激！我该如何将缩略图（UIImage）与其所属的视频一起写入我的文档目录？

以下是我的代码：

func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : Any]) {

    let mediaType = info[UIImagePickerControllerMediaType] as! NSString
    dismiss(animated: true, completion: nil)

    if mediaType == kUTTypeMovie {
        // Componenets for a unique ID for the video
        var uniqueVideoID = ""
        var videoURL:NSURL? = NSURL()
        var uniqueID = ""
        uniqueID = NSUUID().uuidString

        // Get the path as URL
        videoURL = info[UIImagePickerControllerMediaURL] as? URL as NSURL?
        let myVideoVarData = try! Data(contentsOf: videoURL! as URL)

        // Write the video to the Document Directory at myVideoVarData (and set the video's unique ID)
        let docPaths = NSSearchPathForDirectoriesInDomains(FileManager.SearchPathDirectory.documentDirectory, FileManager.SearchPathDomainMask.userDomainMask, true)
        let documentsDirectory: AnyObject = docPaths[0] as AnyObject
        uniqueVideoID = uniqueID  + "VIDEO.MOV"
        let docDataPath = documentsDirectory.appendingPathComponent(uniqueVideoID) as String
        try? myVideoVarData.write(to: URL(fileURLWithPath: docDataPath), options: [])
        print("docDataPath under picker ", docDataPath)
        print("Video saved to documents directory")

        // Create a thumbnail image from the video (first frame)
        let asset = AVAsset(url: URL(fileURLWithPath: docDataPath))
        let assetImageGenerate = AVAssetImageGenerator(asset: asset)
        assetImageGenerate.appliesPreferredTrackTransform = true
        let time = CMTimeMake(asset.duration.value / 3, asset.duration.timescale)
        if let videoImage = try? assetImageGenerate.copyCGImage(at: time, actualTime: nil) {
            // Add thumbnail & video path to Post object
            let video = Post(pathToVideo: URL(fileURLWithPath: docDataPath), thumbnail: UIImage(cgImage: videoImage))
            posts.append(video)
            print("Video saved to Post object")
        }
    }
}

- KingTim

你正在本地生成图像并将其保存到对象中，因为图像未直接保存在文档中或在任何数据库中缓存。你无法恢复它。你可以创建一个缓存管理器，将图像保存在“DocumentDirectory”中，然后以与视频相同的方式保存该URL，或者将图像的NSData保存在数据库中，并将其呈现回UIImage。 - Ankit

1个回答

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- Ashwin Kanjariya · Accepted Answer

一个建议：按照苹果的指导方针，如果可以再次下载，请将图像保存到Library/Caches中。

就这么简单：

func saveImageToDocumentDirectory(_ chosenImage: UIImage) -> String {
        let directoryPath =  NSHomeDirectory().appending("/Documents/")
        if !FileManager.default.fileExists(atPath: directoryPath) {
            do {
                try FileManager.default.createDirectory(at: NSURL.fileURL(withPath: directoryPath), withIntermediateDirectories: true, attributes: nil)
            } catch {
                print(error)
            }
        }
        let filename = NSDate().string(withDateFormatter: yyyytoss).appending(".jpg")
        let filepath = directoryPath.appending(filename)
        let url = NSURL.fileURL(withPath: filepath)
        do {
            try UIImageJPEGRepresentation(chosenImage, 1.0)?.write(to: url, options: .atomic)
            return String.init("/Documents/\(filename)")

        } catch {
            print(error)
            print("file cant not be save at path \(filepath), with error : \(error)");
            return filepath
        }
    }

Swift4:

func saveImageToDocumentDirectory(_ chosenImage: UIImage) -> String {
        let directoryPath =  NSHomeDirectory().appending("/Documents/")
        if !FileManager.default.fileExists(atPath: directoryPath) {
            do {
                try FileManager.default.createDirectory(at: NSURL.fileURL(withPath: directoryPath), withIntermediateDirectories: true, attributes: nil)
            } catch {
                print(error)
            }
        }

        let dateFormatter = DateFormatter()
        dateFormatter.dateFormat = "yyyyMMddhhmmss"

        let filename = dateFormatter.string(from: Date()).appending(".jpg")
        let filepath = directoryPath.appending(filename)
        let url = NSURL.fileURL(withPath: filepath)
        do {
            try chosenImage.jpegData(compressionQuality: 1.0)?.write(to: url, options: .atomic)
            return String.init("/Documents/\(filename)")

        } catch {
            print(error)
            print("file cant not be save at path \(filepath), with error : \(error)");
            return filepath
        }
    }