NSError 解析

        NSDictionary * errorInfo = error.userInfo;
        if ([[errorInfo allKeys] containsObject: @"com.alamofire.serialization.response.error.data"]){
           NSData * errorData = errorInfo[@"com.alamofire.serialization.response.error.data"];
            NSDictionary * errorDict =  [NSJSONSerialization JSONObjectWithData: errorData options:NSJSONReadingAllowFragments error:nil];
           NSNumber * errorCodeNum = errorDict[@"err_code"];
            NSLog(@"=====%@====", errorCodeNum);
       }