downloadImageFunc.swift

func downloadImage(from storageImagePath: String) {
        // 1. Get a filePath to save the image at
        let paths = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)
        let documentsDirectory = paths[0]
        let filePath = "file:\(documentsDirectory)/myimage.jpg"
        // 2. Get the url of that file path
        guard let fileURL = URL(string: filePath) else { return }

        // 3. Start download of image and write it to the file url
        storageDownloadTask = storageRef.child(storageImagePath).write(toFile: fileURL, completion: { (url, error) in
            // 4. Check for error
            if let error = error {
                print("Error downloading:\(error)")
                return
                // 5. Get the url path of the image
            } else if let imagePath = url?.path {
                // 6. Update the unicornImageView image
                self.unicornImageView.image = UIImage(contentsOfFile: imagePath)
            }
        })
        // 7. Finish download of image
    }