Question

我在注册后尝试创建用户个人资料

如何正确地将用户信息从Firebase数据库上传到个人资料屏幕

   DatabaseRef = Database.database().reference()
     let userID = Auth.auth().currentUser?.uid
          DatabaseRef.child("users").child(userID!).observeSingleEvent(of: .value, with: { (snapshot) in
            // Get user value
            let value = snapshot.value as? NSDictionary
            let username = value?["username"] as? String ?? "username"
           let dict: Dictionary<AnyHashable, Any>? = ["photo": "url of photo"]

         if let profileImageUrl = dict?["photo"] as? String, let url = URL(string: profileImageUrl) {

            URLSession.shared.dataTask(with: url) { (data, response, error) in
             DispatchQueue.main.async {
                        if let imageData = data{
                                self.ProfileImage.image = UIImage(data: imageData)
                            }else{

                        }
                    }
                    self.UsernameText.text = username
                self.DisplayText.text = username

                print(error?.localizedDescription as Any)
                return

Answer 1

您应始终避免强行打开包装。相反，您可以检查url是否不为零，并且仅在url具有某些值时才发送请求。

if let profileImageUrl = dict?["photo"] as? String, let url = URL(string: profileImageUrl) {
    URLSession.shared.dataTask(with: notNillUrl) { (data, response, error) in

我可以看到您的url是由profileImageUrl创建的，URL格式可能不正确（如不带“ http” /“ https”），因此有必要检查URL创建的表单字符串是否为不零。我将保留以前的答案，因为这可能对其他人有帮助。

检查此URL为何为零将是很好的。也许您正在尝试创建这样的无效URL：

let url = URL(string: "https://this is not woking.com") //or
let url = URL(string: "https://test.com/?a=this won't work")

在这种情况下，最好使用URLComponents：

var components = URLComponents()

components.scheme = "https"
components.host = "api.github.com"
components.path = "/search / repositories"
components.queryItems = [
    URLQueryItem(name: "q", value: "CodableSaveLoad"),
    URLQueryItem(name: "other", value: "text with space")
]

print(components.url)

Answer 2

当您使用（！）强行解开可选值时，程序崩溃，您将收到该错误。取而代之的是，用防护罩安全地打开可选包装。

guard let profileImageUrl = dict?["photo"] as? String else {
    print("something wrong, dict["photo"] cannot be cast to String")
    return
}

let url = URL(string: profileImageUrl)
URLSession.shared.dataTask(with: url!) { (data, response, error) in
                    if error != nil {
                        print(error!)
                        return
                    }
}

如何正确更新用户个人资料屏幕

2 个答案: