Swift 3 将图像添加到文档并检索

Question

我觉得我缺少一些重要的东西，因为我没有收到任何错误或空值，但每当我尝试检索我的图像时，它returns "" 因为它不存在？

这就是我传递图像数据的方式：

URLSession.shared.dataTask(with: url! as URL, completionHandler:{ (data, response, error) in
   //if download error
   if error != nil{
   print(error!)
   return
}
guard let imageData = UIImage(data: data!) else { return }
DispatchQueue.main.async{
   self.imgPortrait.image = imageData
   ImagePortrait().saveImageDocumentDirectory(image: imageData)
}

数据显示在imgPortrait 上完全没问题。以下是其余函数，其中：/\(userUID)/\(CharacterSelection.sharedInstance.getActiveCharacterName()) 是可选的。当它去检索图像并保存它时，我可以确认路径完全相同。我觉得这就是我使用createFile 保存图像的方式，但我不确定。

   func saveImageDocumentDirectory(image: UIImage){
        if let userUID = Auth.auth().currentUser?.uid{
            let fileManager = FileManager.default
            let paths = (getDirectoryPath() as NSString).appendingPathComponent("/\(userUID)/\(CharacterSelection.sharedInstance.getActiveCharacterName())/characterPortrait.png")
            createDirectory(name: (getDirectoryPath() as NSString) as String)
            let imageData = UIImagePNGRepresentation(image)
            fileManager.createFile(atPath: paths as String, contents: imageData, attributes: nil)
        }
    }

    func getDirectoryPath() -> String {
        let paths = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)
        let documentsDirectory = paths[0]
        return documentsDirectory
    }

    func getImage() -> String{
        if let userUID = Auth.auth().currentUser?.uid{
            let fileManager = FileManager.default
            let imagePath = (self.getDirectoryPath() as NSString).appendingPathComponent("/\(userUID)/\(CharacterSelection.sharedInstance.getActiveCharacterName())/characterPortrait.png")
            if fileManager.fileExists(atPath: imagePath){
                return imagePath
            }else{
                print("No Image")
                return ""
            }
        }
        else{
            return ""
        }
    }

    func createDirectory(name: String){
        let fileManager = FileManager.default
        let paths = (getDirectoryPath() as NSString).appendingPathComponent(name)
        if !fileManager.fileExists(atPath: paths){
            try! fileManager.createDirectory(atPath: paths, withIntermediateDirectories: true, attributes: nil)
        }else{
            print("Directory is already created.")
        }
    }

提前致谢！

Answer 1

几个小时后，我想通了。看起来目录没有被创建。解决方法：

func saveImageDocumentDirectory(image: UIImage){
        if let userUID = Auth.auth().currentUser?.uid{
            let fileURL = try! FileManager.default.url(for: .documentDirectory, in: .userDomainMask, appropriateFor: nil, create: true).appendingPathComponent("\(userUID)_\(CharacterSelection.sharedInstance.getActiveCharacterName())_characterPortrait.png")

            do {
                try UIImagePNGRepresentation(image)?.write(to: fileURL, options: .atomic)
            } catch {
                print(error)
            }
        }
    }

    func getImage() -> UIImage{
        if let userUID = Auth.auth().currentUser?.uid{
            let nsDocumentDirectory = FileManager.SearchPathDirectory.documentDirectory
            let nsUserDomainMask = FileManager.SearchPathDomainMask.userDomainMask
            let paths = NSSearchPathForDirectoriesInDomains(nsDocumentDirectory, nsUserDomainMask, true)
            if let dirPath = paths.first
            {
                let imageURL = URL(fileURLWithPath: dirPath).appendingPathComponent("\(userUID)_\(CharacterSelection.sharedInstance.getActiveCharacterName())_characterPortrait.png")
                if let image = UIImage(contentsOfFile: imageURL.path){
                    return image
                }
                else{
                    print("Image isn't found.")
                    return UIImage(named: "default_portrait.png")!
                }

            }
            else{
                print("Image isn't found.")
                return UIImage(named: "default_portrait.png")!
            }
        }
        else{
            print("Image isn't found.")
            return UIImage(named: "default_portrait.png")!
        }
    }