swift - 在 Swift 中使用 Firebase，如何从集合中提取文档以在 TextView 中显示？

Question

登录应用程序后，在设置页面中，SettingsViewController ，我希望用户能够在 TextView 中查看他们的信息。但是，无论读取数据的方法如何，我总是收到 Swift 编译器警告:

Cast from '[String]' to unrelated type 'String' always fails

这是我的代码:

func textViewFill() {

    let db = Firestore.firestore()

    db.collection("users").getDocuments() { (querySnapshot, err) in
        if let err = err {
            print("Error getting documents: \(err)")
        } else {
            for document in querySnapshot!.documents {
                print("\(document.documentID) => \(document.data())")
                let firstName = ["firstName"] as? String ?? ""
                let lastName = ["lastName"] as? String ?? ""
                let email = ["email"] as? String ?? ""
                self.firstNameTextView.text = firstName
                self.lastNameTextView.text = lastName
                self.emailTextView.text = email
            }
        }
    }
}

当我尝试将文档定义为字符串时出现警告:

let firstName = ["firstName"] as? String ?? ""
let lastName = ["lastName"] as? String ?? ""
let email = ["email"] as? String ?? ""

有没有办法将其显示为文本？

Answer 1

您正在尝试转换 Array如 String这里。这是您需要的:

let firstName = document.get("firstName") as? String ?? ""
let lastName = document.get("lastName") as? String ?? ""
let email = document.get("email") as? String ?? ""