Show error messages in UIAlertView by UIAlerView+AFNetworking - objective-c

Question

There is a categroy UIAlertView+AFNetworking.h ship with AFNetworking 2.0. And I use it to show error messages in my App like this:
[UIAlertView showAlertViewForTaskWithErrorOnCompletion:task delegate:nil]
But I want to add some other messages in the message of UIAlertView.
i.e.:
StatusCode: 422
JSON Data: {"errors":{"detail":"Wrong password"}}
How to get "Wrong password" and show in a UIAlertView by the functions in UIAlertView+AFNetworking?

Answer 1

UIAlertView+AFNetworking category uses error messages from NSError – localizedDescription, localizedRecoverySuggestion and localizedFailureReason. AFNetworking generates NSError on failure, however, you must write your own responseSerializer to set your custom error messages there.
This topic has been thoroughly discussed on GitHub and I use solution based #camdez's code snippet.
My error response messages from API looks like this:
{ error: { message: "This username already exists" } }
Now, I've subclassed AFJSONResponseSerializer and when an error occurs, I save the error message to the NSError instance.
CustomResponseSerializer.h
#interface CustomResponseSerializer : AFJSONResponseSerializer
#end
CustomResponseSerializer.m
#implementation CustomResponseSerializer
- (id)responseObjectForResponse:(NSURLResponse *)response
data:(NSData *)data
error:(NSError *__autoreleasing *)error
{
id JSONObject = [super responseObjectForResponse:response data:data error:error]; // may mutate `error`
if (*error && [JSONObject objectForKey:#"error"]) {
NSMutableDictionary *mutableUserInfo = [(*error).userInfo mutableCopy];
mutableUserInfo[NSLocalizedFailureReasonErrorKey] = [[JSONObject objectForKey:#"error"] objectForKey:#"message"];
NSError *newError = [NSError errorWithDomain:(*error).domain code:(*error).code userInfo:[mutableUserInfo copy]];
(*error) = newError;
}
return JSONObject;
}
#end
Finally, you need to set appropriate responseSerializer on AFHTTPSessionManager (or AFHTTPRequestOperationManager if you use NSURLConnection API) instance. If you subclass this class as I do, you can simply do it in your init method by following:
self.responseSerializer = [CustomResponseSerializer serializer];