ios - 不确定在代码中放置 storageRef.downloadURL 的位置

Question

将 Firebase 更新到版本 4 并更正所有 200 个错误后，我收到 2 条警告，导致我的应用程序崩溃。我查找了这个错误并尝试了解决方案但没有成功:

storageReference.downloadURLWithCompletion()

一定是我做错了:

func setUserInfo(_ user: User!, usersname: String, email: String, password: String, cell: String, data: Data!) {

    // Create Path for User Image
    let imagePath = "images/riders/\(user.uid)/Profile Pic/userPic.jpg"

    // Create image Reference
    let imageRef = rDataService.Instance.storageRef.child(imagePath)

    // Create Metadata for the image
    let metaData = StorageMetadata()
    metaData.contentType = "image/jpeg"

    // Save the user Image in the Firebase Storage File
    imageRef.putData(data as Data, metadata: metaData) { (metaData, error) in
        if error == nil {
            let changeRequest = user.createProfileChangeRequest()
            changeRequest.displayName = usersname
            changeRequest.photoURL = metaData?.downloadURL()
            changeRequest.commitChanges(completion: { (error) in

                if error == nil {
                    self.saveUser(user, usersname: usersname, email: email, password: password, cell: cell)

                } else {
                    print(error!.localizedDescription)
                }
            })

        } else {
            print(error!.localizedDescription)
        }
    }

}

错误发生在这一行:

changeRequest.photoURL = metaData?.downloadURL()

编辑

调整后，在这一行得到警告:

if let profilepicMetaData = profilepicMetaData {

error: Value 'profilepicMetaData' was defined but never used; consider  replacing with boolean test

应用仍然崩溃:

// Save the user profile Image in the Firebase Storage File
    imageRef.putData(data as Data, metadata: profilepicMetaData) { (profilepicMetaData, error) in
        if let profilepicMetaData = profilepicMetaData {
            imageRef.downloadURL(completion: { (url, error) in

                guard let url = url else {
                    if let error = error {
                        print(error)
                    }
                    return
                }
                let changeRequest = user.createProfileChangeRequest()
                changeRequest.displayName = usersname
                changeRequest.photoURL = url

                changeRequest.commitChanges(completion: { (error) in

                if error == nil {
                    self.saveUser(user, usersname: usersname, email: email, password: password, year: year, makeAndModel: makeAndModel, cell: cell, plateNo: plateNo)

                } else {
                    print(error!.localizedDescription)
                }
            })
        })

        } else {
            print(error!.localizedDescription)
        }
    }

崩溃!

Answer 1

需要使用原始存储引用对象imageRef获取下载地址。 (请通过代码查看注释):

imageRef.putData(data, metadata: profilepicMetaData) {
    // use if let to unwrap the metadata returned to make sure the upload was successful. You can use an underscore to ignore the result
    if let _ = $0 {
        // start the async method downloadURL to fetch the url of the file uploaded
        imageRef.downloadURL {
            // unwrap the URL to make sure it is not nil
            guard let url = $0 else {
                // if the URL is nil unwrap the error, print it 

                if let error = $1 { 
                    // you can present an alert with the error localised description
                    print(error) 
                }
                return
            }
            // your createProfileChangeRequest code  needs to be run after the download url method completes. If you place it after the closure it will be run before the async method finishes.
            let changeRequest = user.createProfileChangeRequest()
            changeRequest.displayName = usersname
            changeRequest.photoURL = url
            changeRequest.commitChanges {
                // unwrap the error and print it
                if let error = $0 {
                    // again you might present an alert with the error
                    print(error)
                } else {
                    // user was updated successfully
                    self.saveUser(user, usersname: usersname, email: email, password: password, year: year, makeAndModel: makeAndModel, cell: cell, plateNo: plateNo)
                }
            }
        }
    } else if let error = $1 {
        // present an alert with the error
        print(error)
    }
}