Question

直到最近，我还没有问题能够从数据库中提取数据 - 并且只有在我决定添加另一个变量（totalDistance）时它才会开始中断，但是在尝试删除这个新编写的代码时，错误仍然存在。

fatal error: unexpectedly found nil while unwrapping an Optional value
(lldb)

当我尝试进入导致错误的“个人资料”页面时，这是我得到的错误，这里是我写的能够写标签的函数 -

let ref = FIRDatabase.database().reference()
        let UserID = FIRAuth.auth()?.currentUser?.uid
        ref.child("user").child(UserID!).observeSingleEvent(of: .value, with: { (snapshot) in
            let value = snapshot.value as? NSDictionary
            let displayname = value?["nickname"] as? String ?? "Nickname Missing"
            let bronzeMedals = value?["bronzeMedals"] as? String ?? "no bronze in db"
            let silverMedals = value?["silverMedals"] as? String ?? "no silver in db"
            let goldMedals = value?["goldMedals"] as? String ?? "no gold in db"
            let totalDistance = value?["totalDistance"] as? String ?? "no total in db"

            print(bronzeMedals, silverMedals, goldMedals)

            self.displaynameLabel.text = ("Username: \(displayname)")
            self.goldmedalsLabel.text = ("Gold medals: \(goldMedals)")
            self.silvermedalsLabel.text = ("Silver medals: \(silverMedals)")
            self.bronzemedalsLabel.text = ("Bronze medals: \(bronzeMedals)")
            self.totaldistanceLabel.text = ("Total distance: \(totalDistance)")
 })

这种调用信息的方法已经完美无缺，直到我试图添加另一个变量，我对此错误感到非常困惑，似乎无法找到解决方法 - 无论我查找多少不同的错误已经得到了回答，所以任何信息都将非常重要并且非常受欢迎。

这是用户的数据库文件 - 正在调用

age: 
"18"
 bronzeMedals: 
"2"
 goldMedals: 
"3"
 nickname: 
"Test Account"
 silverMedals: 
"5"
 totalDistance: 
"2"

Answer 1

您确实需要更改代码，以便不使用选项。

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

guard let user = FIRAuth.auth()?.currentUser else { return }

ref.child("user").child(user.uid).observeSingleEvent(of: .value, with: { (snapshot) in

    guard let value = snapshot.value as? Dictionary<String,String> else { return }

    let displayname = value["nickname"] ?? "Nickname Missing"

    let bronzeMedals = value["bronzeMedals"] ?? "no bronze in db"

    let silverMedals = value["silverMedals"] ?? "no silver in db"

    let goldMedals = value["goldMedals"] ?? "no gold in db"

    let totalDistance = value["totalDistance"] ?? "no total in db"


    // Update Labels

    self.displaynameLabel.text = ("Username: \(displayname)")

    self.goldmedalsLabel.text = ("Gold medals: \(goldMedals)")

    self.silvermedalsLabel.text = ("Silver medals: \(silverMedals)")

    self.bronzemedalsLabel.text = ("Bronze medals: \(bronzeMedals)")

    self.totaldistanceLabel.text = ("Total distance: \(totalDistance)")
})

从Firebase调用时解包可选时的致命错误nil

1 个答案: