ios - 如何从文件目录保存和加载图像 - Swift 4

Question

我正在尝试将图像保存到文件目录并从文件目录加载图像，但是我的 writeImageToPath 函数向控制台打印了以下错误，并指出该文件不存在。

控制台

Write image to directory

File exists Write image

Error Write image to directory File does NOT exist -- file:///Users/user/Library/Developer/CoreSimulator/Devices/70EAC77D-9F3C-4AFC-8CCA-A7B9B895BDE6/data/Containers/Data/Application/DDAF2EBD-5DDA-4EA6-95D3-6785B74A0B09/Documents/upload/http://i.annihil.us/u/prod/marvel/i/mg/a/f0/5202887448860 -- is available for use Write image Error Writing Image: Error Domain=NSCocoaErrorDomain Code=4 "The file “5202887448860” doesn’t exist." UserInfo={NSFilePath=/Users/user/Library/Developer/CoreSimulator/Devices/70EAC77D-9F3C-4AFC-8CCA-A7B9B895BDE6/data/Containers/Data/Application/DDAF2EBD-5DDA-4EA6-95D3-6785B74A0B09/Documents/upload/http://i.annihil.us/u/prod/marvel/i/mg/a/f0/5202887448860, NSUnderlyingError=0x600003b04ab0 {Error Domain=NSPOSIXErrorDomain Code=2 "No such file or directory"}}

这是我的代码，我不确定我哪里出错了

// The images are loaded from the web and displayed in the cell.imageView.image

  if let thumbnail = product["thumbnail"] as? [String: Any],
     let path = thumbnail["path"] as? String,
     let fileExtension = thumbnail["extension"] as? String {

  //Save image to directory
  if image != nil {
     writeImageToPath(path, image: image!)
  }

  }


// Write image to directory
func writeImageToPath(_ path: String, image: UIImage) {
    print("Write image to directory")

    let uploadURL = URL.createFolder(folderName: "upload")!.appendingPathComponent(path)

    if !FileManager.default.fileExists(atPath: uploadURL.path) {
        print("File does NOT exist -- \(uploadURL) -- is available for use")

        let uploadURL = URL.createFolder(folderName: "upload")!.appendingPathComponent(path)

        if let data = UIImageJPEGRepresentation(image, 0.9) {
            do {
                print("Write image")
                try data.write(to: uploadURL)
            }
            catch {
                print("Error Writing Image: \(error)")
            }

        } else {
            print("Image is nil")
        }
    } else {
        print("This file exists -- something is already placed at this location")
    }

}


// load image from directory
func loadImageFromPath(_ path: String) -> UIImage? {

    let documentsURL = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)[0]

    let folderURL = documentsURL.appendingPathComponent("upload")

    let fileURL = folderURL.appendingPathComponent(path)

    if FileManager.default.fileExists(atPath: fileURL.path) {
        //Get Image And upload in server
        print("fileURL.path \(fileURL.path)")

        do{
            let data = try Data.init(contentsOf: fileURL)
            let image = UIImage(data: data)
            return image
        }catch{
            print("error getting image")
        }
    } else {
        print("No image in directory")
    }

    return nil
}


extension URL {
static func createFolder(folderName: String) -> URL? {
    let fileManager = FileManager.default
    // Get document directory for device, this should succeed
    if let documentDirectory = fileManager.urls(for: .documentDirectory,
                                                in: .userDomainMask).first {
        // Construct a URL with desired folder name
        let folderURL = documentDirectory.appendingPathComponent(folderName)
        // If folder URL does not exist, create it
        if !fileManager.fileExists(atPath: folderURL.path) {
            do {
                // Attempt to create folder
                try fileManager.createDirectory(atPath: folderURL.path,
                                                withIntermediateDirectories: true,
                                                attributes: nil)
            } catch {
                // Creation failed. Print error & return nil
                print(error.localizedDescription)
                return nil
            }
        }
        // Folder either exists, or was created. Return URL
        return folderURL
    }
    // Will only be called if document directory not found
    return nil
}
}

如何正确保存和加载目录中的图像？

Answer 1

class MyImageClass {
    func writeImageToPath(_ path:String, image:UIImage) {
        let uploadURL = URL.createFolder(folderName: "upload")!.appendingPathComponent(path)

        if !FileManager.default.fileExists(atPath: uploadURL.path) {
            print("File does NOT exist -- \(uploadURL) -- is available for use")
            let data = image.jpegData(compressionQuality: 0.9)
            do {
                print("Write image")
                try data!.write(to: uploadURL)
            }
            catch {
                print("Error Writing Image: \(error)")
            }
        }
        else {
            print("This file exists -- something is already placed at this location")
        }
    }
}

extension URL {
    static func createFolder(folderName: String) -> URL? {
        let fileManager = FileManager.default
        // Get document directory for device, this should succeed
        if let documentDirectory = fileManager.urls(for: .documentDirectory,
                                                in: .userDomainMask).first {
            // Construct a URL with desired folder name
            let folderURL = documentDirectory.appendingPathComponent(folderName)
            // If folder URL does not exist, create it
            if !fileManager.fileExists(atPath: folderURL.path) {
                do {
                    // Attempt to create folder
                    try fileManager.createDirectory(atPath: folderURL.path,
                                                withIntermediateDirectories: true,
                                                attributes: nil)
                } catch {
                    // Creation failed. Print error & return nil
                    print(error.localizedDescription)
                    return nil
                }
            }  
            // Folder either exists, or was created. Return URL
            return folderURL
        }
        // Will only be called if document directory not found
        return nil
    }
}

var saving = MyImageClass()
saving.writeImageToPath("whereIWantToSaveTheImageTo", image: UIImage(named: "myImage"))

引用资料 Create Directory in Swift 3.0

我没有测试成像是否有效，但是，这确实创建了一个名为“上传”的文件夹，您每次都可以调用它。该扩展有一个名为 createFolder 的方法，它会为您调用的任何内容返回一个文件夹，如果它不存在则创建它。我们可以只检查文件夹中的指定路径，然后如果它可用，我们就可以写入它。我也只重写了 writeImageToPath 部分。

注意:

在 Playground 上测试过这个......

结果是:

File does NOT exist -- file:///var/folders/vs/nlj__xh93vs0f8wzcgksh_zh0000gn/T/com.apple.dt.Xcode.pg/containers/com.apple.dt.playground.stub.iOS_Simulator.MyPlayground-67A67A07-51FF-4DF4-BE80-02E7FDAFA1CA/Documents/upload/whereIWantToSaveTheImageTo -- is available for use
Write image