Unable to obtain origin of NSLog in a Parse block? - ios

Question

I am using the following code to log in a user to my application using parse.com
[PFUser logInWithUsernameInBackground:usernameString password:passwordString
block:^(PFUser *user, NSError *error) {
if (user) {
// Do stuff after successful login.
NSLog(#"The user has logged in");
} else {
// The login failed. Check error to see why.
}
}];
The code works great and is documented on the Parse.com API Documentation HERE
My problem however is that I want to be able to show an alert to users when their login credentials come back with with an error, currently I get the following error on my console when I try to sign in with invalid credentials: Error: invalid login credentials (Code: 101, Version: 1.2.19)
Thats great, but I have looked everywhere and cant seem to find where that code, is being created... I am looking for it so that I can add different error messages for to my users: i.e.
if ([errorString rangeOfString:#"username"].location == NSNotFound) {
//the issue is not username related
} else
{
NSLog= (#"The username has been taken");
}
Any idea how I can find the string that contains the error and examine it so that I may act accordingly to the error?

Answer 1

the parse error codes are all documented here:
https://parse.com/docs/ios/api/Classes/PFConstants.html
101 is kPFErrorObjectNotFound
and means 'Object doesn't exist, or has an incorrect password.'
during a login it is likely more the later ;)
so:
if(error.code == kPFErrorObjectNotFound) {
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:#"parse login error" message:#"Invalid credentials" delegate:nil cancelButtonTitle:#"ok"];
[alert show];
}
dont use the error string of an NSError as you can't really tell if it is suitable for display.
still it is likely in localizedDescription or some other userInfo field

Answer 2

If you look at the documentation for NSError you will see that its userInfo property is a dictionary. From your NSLog you can see that the error key contains the string you are after, so you can access it with
NSString *errorMessage=[error.userInfo objectForKey:#"error"];
Although, rather than parsing strings it is safer to check the error.code value for 101, possibly displaying the error message for more detail. Checking the error code rather than the string will ensure that a change in the string by Parse won't break your code