如何从NSError.description中获取[错误] ：？

Question

I am trying to create a UIAlertView that displays only the error of NSError.description .

For example:

var alert = UIAlertView(title: "Oops!", message: error.description, delegate: self, cancelButtonTitle: "OK")
alert.show()

Say the error.description outputs:

2015-02-01 02:26:43.227 UserLogin[249:13655] [Error]: missing username (Code: 200, Version: 1.6.2)

How can I just get the [Error]: missing username in a String ? I am new to app development and I simply want my error messages to make sense to the user and to be simple.

If this does not make sense, I am using Parse and I am working on a registration form. If the error occurs such as "missing username" , "username taken" , etc. I just wanted to find a way to get a simple error popup to say "username taken" .

Answer 1

You can use the localizedDescription property of NSError .

Instead of error.description use error.localizedDescription

var alert = UIAlertView(title: "Oops!", message: error.localizedDescription, delegate: self, cancelButtonTitle: "OK")
alert.show()

Note:

UIAlertView is deprecated in iOS 8, use UIAlertController instead.

Answer 2

Try using this:

if let dic  = error?.userInfo {
   let errorString = dic[NSUnderlyingErrorKey]?.localizedDescription
   var alert = UIAlertView(title: "Oops!", message:errorString, delegate: self, cancelButtonTitle: "OK")
   alert.show()
}

Answer 3

Before you go in that direction, you should think very, very hard whether the NSError that you received is meant to be seen by a user. Many NSErrors are meant to be examined by a programmer only. In this case, "missing username" seems a strong indication that you, the programmer, made a mistake by sending a request without a username and shouldn't have done that in the first place. So showing an error alert may be the totally wrong solution.