隐含地从'String？'强制表达了表达式 去任何

Question

我有一些像这样的错误"表达式隐式强制来自'String？' 任何"这是我的代码:

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
    // Override point for customization after application launch.

    FIRApp.configure()
    FIRAuth.auth()?.signIn(withEmail: "myemail@gmail.com", password: "mypassword", completion: { (user, error) in
        if (error != nil) {
            print(user?.email)
        }else {
            print(error?.localizedDescription)
        }
    })

    return true
}

这一行出错

print(user?.email)

和

print(error?.localizedDescription)

请帮我

Answer 1

该print功能需要一组Any参数.String是一个Any.在这种情况下,Xcode告诉您它隐式地将可选字符串强制转换为Any对象(通过转换String值Optional(value)).

要避免此警告,您只需使用默认值或解包 String?

print(user?.email ?? "User instance is nil")
print(user!.email)