swift - 在 Swift 函数之外访问变量

Question

如何从内部获取 firstName 的值:

func saveImage(name: String, postURL:URL, completion: @escaping ((_ url: URL?) -> ())){

    //Get sspecific document from current user
    let docRef = Firestore.firestore().collection("users").whereField("uid", isEqualTo: Auth.auth().currentUser?.uid ?? "")

    var firstName = ""

    // Get data
    docRef.getDocuments { (querySnapshot, err) in

        var firstName = ""

        if let err = err {
            print("ERROR: ")
            print(err.localizedDescription)
            return
        } else if querySnapshot!.documents.count != 1 {
            print("More than one documents or none")
        } else {
            let document = querySnapshot!.documents.first
            let dataDescription = document?.data()
            firstName = dataDescription?["firstname"] as! String



        }

    } 


//         This uploads the data

    let dict = ["title": postDescriptionTitle.text!,
                "description": postDescription.text!,
                "Address": addressField.text!,
                "Zipcode": zipcodeField.text!,
                "timestamp": [".sv":"timestamp"],
                "Author":firstName,
                "postUrl": postURL.absoluteString]
        as [String: Any]
    self.ref.child("post").childByAutoId().setValue(dict)

}

看起来它超出了范围，我如何在不将其存储在另一个变量中的情况下存储或访问它？

如您所见，我正在尝试将变量 firstName 上传到数据库。所以在这部分:“作者”:名字，我应该得到值(value)，这样我就可以把它交给作者

Answer 1

只需将“上传数据”部分移动到完成 block 中，如下所示:

  func saveImage(name: String, postURL:URL, completion: @escaping ((_ url: URL?) -> ())) {
        //Get sspecific document from current user
        let docRef = Firestore.firestore().collection("users").whereField("uid", isEqualTo: Auth.auth().currentUser?.uid ?? "")

        // Get data
        docRef.getDocuments { (querySnapshot, err) in

            if let err = err {
                print("ERROR: ")
                print(err.localizedDescription)
                return
            } else if querySnapshot!.documents.count != 1 {
                print("More than one documents or none")
            } else {
                let document = querySnapshot!.documents.first
                let dataDescription = document?.data()
                let firstName = dataDescription?["firstname"] as! String
                //         This uploads the data
                let dict = ["title": self.postDescriptionTitle.text!,
                            "description": self.postDescription.text!,
                            "Address": self.addressField.text!,
                            "Zipcode": self.zipcodeField.text!,
                            "timestamp": [".sv":"timestamp"],
                            "Author": firstName,
                            "postUrl": postURL.absoluteString] as [String: Any]
                self.ref.child("post").childByAutoId().setValue(dict)
            }
        }
    }

此外，您在 saveImage 函数中使用完成参数是为了什么？