Question

Xcode显示代码永远不会被执行的警告，但我不明白为什么。任何人都可以开导我吗？（错误发生在内部if和else语句中，在完成处理程序内，对于两个验证语句）

- (IBAction)siginButtonPressed:(UIButton *)sender
{
    if (isLogin)
{
    [[FIRAuth auth] signInWithEmail:_usernameTextField.text
                           password:_passwordTextField.text
                         completion:^(FIRUser *user, NSError *error)
         {
             if (FIRAuthErrorCodeUserNotFound)
             {
                 _credentialVerification.text = @"Invalid Credentials";
                 _entryValidation.text = @"An account with the listed credentials was not found, please proceed to registration screen via the navigation bar at the top of the applications user interface";
             }
             else
             {
 /*(Warning 1)*/ _credentialVerification.text = @"Valid Credentials";
                 [self performSegueWithIdentifier:@"toMainScreen" sender:self];
             }
         }

     ];
}
else
{
    [[FIRAuth auth] createUserWithEmail:_usernameTextField.text
                               password:_passwordTextField.text
                             completion:^(FIRUser *_Nullable user, NSError *_Nullable error)
         {
             if (FIRAuthErrorCodeInvalidEmail)
             {
                 _credentialVerification.text = @"Invalid Email";
             }
             else
             {

 /*(Warning 2)*/ _entryValidation.text = @"Account creation was succesful, please proceed to the login screen via the navigation bar at the top of the applications user interface";
             }
         }

     ];
}

}

编辑：

- (IBAction)siginButtonPressed:(UIButton *)sender
{
if (isLogin)
{
    [[FIRAuth auth] signInWithEmail:_usernameTextField.text
                           password:_passwordTextField.text
                         completion:^(FIRUser *user, NSError *error)
                         {
                             if (error.code == FIRAuthErrorCodeUserNotFound)
                             {
                                 _credentialVerification.text = @"Invalid Credentials";
                                 _entryValidation.text = @"An account with the listed credentials was not found, please proceed to registration screen via the navigation bar at the top of the applications user interface";
                             }
                             else
                             {
                                 _credentialVerification.text = @"Valid Credentials";
                                 [self performSegueWithIdentifier:@"toMainScreen" sender:self];
                             }
                         }
     ];
}
else
{
    [[FIRAuth auth] createUserWithEmail:_usernameTextField.text
                               password:_passwordTextField.text
                             completion:^(FIRUser *_Nullable user, NSError *_Nullable error)
                             {
                                 if (error.code == FIRAuthErrorCodeInvalidEmail)
                                 {
                                     _credentialVerification.text = @"Invalid Email";
                                 }
                                 else
                                 {
                                     _entryValidation.text = @"Account creation was succesful, please proceed to the login screen via the navigation bar at the top of the applications user interface";
                                 }
                             }
     ];
}
}

Answer 1

您的代码中的问题是您正在检查枚举，因为枚举的值不为零，因此它将始终为true并且不会进入else部分，因此您需要更改两个if语句中的条件以检查错误像这样的代码（我不确定语法，但希望你能得到这个想法）

if (error.code == FIRAuthErrorCodeUserNotFound)
if (error.code == FIRAuthErrorCodeInvalidEmail)

<强>更新

修改if if else语句如下：

if (error) {
       NSLog(@"%@", error)
}else {
       //code when there is no error    
}

Answer 2

您无法检查完成处理程序NSError，这就是编译器发出此警告的原因。因此，请在signInWithEmail

中进行检查

                          if (error.code == FIRAuthErrorCodeUserNotFound)
                             {
                                 _credentialVerification.text = @"Invalid Credentials";
                                 _entryValidation.text = @"An account with the listed credentials was not found, please proceed to registration screen via the navigation bar at the top of the applications user interface";
                             }
                             else
                             {
                _credentialVerification.text = @"Valid Credentials";
                                 [self performSegueWithIdentifier:@"toMainScreen" sender:self];
                             }

同样适合您的createUserWithEmail。希望它可以帮到你。

代码永远不会执行错误

2 个答案: