类型“ StorageReference”的值没有成员“子”

Question

打开项目后，我总是会遇到这个问题。我该怎么办？

import UIKit
import Firebase

class FIRImage
{
    var image: UIImage
    var downloadURI: String?
    var ref: StorageReference!

    init(image: UIImage) {
        self.image = image
    }
}

extension FIRImage
{
    func saveProfileImage(_ userUID: String, _ completion: @escaping (Error?) -> Void)
    {
        let resizedImage = image.resized()
        let imageData = UIImageJPEGRepresentation(resizedImage, 0.9)

        ref = StorageReference.profileImages.reference().child(userUID)
        downloadURI = ref.debugDescription

        ref.put(imageData!, metadata: nil) { (metaData, error) in
            completion(error)
        }
    }

    func save(_ uid: String, completion: @escaping (Error?) -> Void)
    {
        let resizedImage = image.resized()
        let imageData = UIImageJPEGRepresentation(resizedImage, 0.9)

        ref = StorageReference.images.reference().child(uid)
        downloadURI = ref.debugDescription

        refput(imageData!, metadata: nil) { (metaData, error) in
            completion(error)
        }
    }
}


extension FIRImage
{
    class func downloadProfileImage(_ uid: String, completion: @escaping (UIImage?, Error?) -> Void)
    {
        StorageReference.profileImages.reference().child(uid).data(withMaxSize: 1 * 1024 * 1024) { (imageData, error) in
            if error == nil && imageData != nil {
                let image = UIImage(data: imageData!)
                completion(image, error)
            } else {
                completion(nil, error)
            }
        }
    }