如何显示一个错误消息，如果电子邮件和密码是无效的firebase swift?

Question

尝试在swift中开发登录页面，然后我想验证错误返回的某些条件。

from print(Error.localizeDescription)我得到一些像

• 密码无效或用户没有密码
• 没有与此标识符对应的用户记录

如何验证基于Error的条件。localizeDescription ?

Auth.auth().signIn(withEmail: email, password: pass, completion: {[weak self] result, Error in
guard let StrongSelf = self else{
return
}

if let Error = Error {
print(Error.localizedDescription)
}

guard Error == nil else{
// in here there is validation of return error (e.g. wrong password, account not exist)
self?.reasonLabel.isHidden=false
self?.reasonLabel.text=Error
return
}

self!.checkinfo()


})

Answer 1

首先，您不应该声明任何属性大写，而是使用小写或驼峰字体。其次，如果您使用[弱self]并设置guard let条件，则使用强self来防止保留循环，并尽量不要使用force unwrap。

Auth.auth().signIn(withEmail: email, password: pass, completion: {[weak self] result, error in
guard let self = self else { return }
if let error = error {
print(error.localizedDescription)
let alert = UIAlertController.configureAlertController(error.localizedDescription)
self.present(alert, animated: true)
return
}
// your logic
/* or 
if let error = error {
print(error.localizedDescription)
UIAlertController. showAlert(error.localizedDescription)
}else{
// your logic
}
*/
/* or

guard let result = result else {
UIAlertController. showAlert(error?.localizedDescription ?? "unknown error")
return
}
// your logic
*/
/* 
or some else, but avoid force unwrap
*/
})

请注意，带有错误检查的if let语句不会阻止整个代码的执行，self!.checkinfo()将被执行，if let error..末尾的return将告诉您的方法他需要停止

extension UIAlertController {
static func configureAlertController(with title: String = "Attention", message: String) -> (UIAlertController){
let alertController = UIAlertController(title: title, message: message, preferredStyle: .alert)
let action = UIAlertAction(title: "ОК",  style: .default) {(action) in}
alertController.addAction(action)

return alertController
}
}

Answer 2

如果您想根据Firebase Authentication引发的错误采取特定的操作，解析Error.localizeDescription并不是最好的方法。相反，检查您在完成处理程序中获得的NSError对象的错误code，再次检查关于处理错误的文档中显示的值。

例如(基于这个repo:

switch error {
case let .some(error as NSError)
where UInt(error.code) == FUIAuthErrorCode.userCancelledSignIn.rawValue:
print("User cancelled sign-in")
case .none:
if let user = authDataResult?.user {
signed(in: user)
}
}
}