ios - swift 火力基地 : Cannot store object of type _SwiftValue at fileURL

Question

我最近刚刚更新到 Swift 3.0 语法和 XCode 8.0。
我在更新后恢复一切正常时遇到了一些麻烦，但我无法解决的一件事是在编写时数据(特别是图像)到数据库我收到以下错误:

Terminating app due to uncaught exception 'InvalidFirebaseData', reason: '(setValue:) Cannot store object of type _SwiftValue at fileURL. Can only store objects of type NSNumber, NSString, NSDictionary, and NSArray.'

这是我目前的写作过程。您能提供的任何帮助将不胜感激!

let roomRef = FIRDatabase.database().reference()

class Data {

    static let dataService = Data()

    fileprivate var _BASE_REF = roomRef
    fileprivate var _ROOM_REF_ = roomRef.child("rooms")

    fileprivate var _BASE_REF2 = roomRef
    fileprivate var _ROOM_REF_2 = roomRef.child("contents")

    var BASE_REF: FIRDatabaseReference {
        return _BASE_REF
    }

    var ROOM_REF: FIRDatabaseReference {
        return _ROOM_REF_
    }

    var storageRef: FIRStorageReference {
        return FIRStorage.storage().reference()
    }


    var fileURL: String!

    func createNewPost(_ user: FIRUser, title: String, author: String, date: String, story: String, data: Foundation.Data) {
        let filePath = "\(user.uid)/\(Int(Date.timeIntervalSinceReferenceDate))"
        let metaData = FIRStorageMetadata()
        metaData.contentType = "image/jpg"
        storageRef.child(filePath).put(data, metadata: metaData) { (metaData, error) in
            if let error = error {
                print("Error Uploading: \(error.localizedDescription)")
                return
            }
            //creating the URL 
            self.fileURL = metaData!.downloadURLs![0].absoluteString
            if let user = FIRAuth.auth()?.currentUser {
                let idRoom = self.BASE_REF.child("rooms").childByAutoId()
                idRoom.setValue(["title": title, "author": author, "date": date, "story": story, "ThumbnailURLFromStorage": self.storageRef.child(metaData!.path!).description, "fileURL": self.fileURL])
            }
        }
    }

    func fetchData(_ callback: @escaping (Room) -> ()) {
    Data.dataService.ROOM_REF.observe(.childAdded, with: { (snapshot) in
            let room = Room(key: snapshot.key, snapshot: snapshot.value as! Dictionary<String, AnyObject>)
            callback(room)
        })
    }
}

Answer 1

经过一番尝试后，我终于弄明白了。在新的 Swift 3 中，Firebase 希望您对所写的内容非常具体。此外，在此过程中不能有任何可选类型。

只需将 String(self.fileURL) 添加到 setValue 函数的末尾就足以解决这个问题。希望这可以帮助其他人!请发表评论以获得进一步的解释。