AFNetworking give me unauthorised error
<p>That is my first time that I am using<code>AFNetworking</code> in my app. I've installed the latest version (3.0) using pods .  Now the problem is the url is working fine in browser and postman but when I get try in app it gives me unauthorised error. I don't know how to authorise. I am adding username and password in header. Can any body help me.
Bellow is my code.</p>

<pre><code>AFHTTPSessionManager *manager = [AFHTTPSessionManager manager];

manager.responseSerializer = [AFHTTPResponseSerializer serializer];

[manager.requestSerializer setValue:username forHTTPHeaderField:@"username"];
[manager.requestSerializer setValue:password forHTTPHeaderField:@"password"];


[manager GET:url parameters:nil progress:nil success:^(NSURLSessionDataTask *task, id responseObject) {

    success(responseObject);

} failure:^(NSURLSessionDataTask *task, NSError *error) {

    failure(error);

}];
</code></pre>

<p>Following is full error log</p>

<pre><code>Error Domain=com.alamofire.error.serialization.response Code=-1011 "Request failed: unauthorized (401)"
 UserInfo={NSUnderlyingError=0x7fa1c3f945b0 {Error
 Domain=com.alamofire.error.serialization.response Code=-1016 "Request
&gt; failed: unacceptable content-type: text/html"
&gt; UserInfo={com.alamofire.serialization.response.error.response=&lt;NSHTTPURLResponse:
 0x7fa1c3d139f0&gt; { URL:
 http://192.168.0.111/guesswhat/getcategories.json } { status code:
 401, headers {
         "Cache-Control" = "no-store, no-cache, must-revalidate, post-check=0, pre-check=0";
         Connection = "Keep-Alive";
         "Content-Length" = 89;
        "Content-Type" = "text/html";
         Date = "Mon, 11 Jan 2016 12:30:55 GMT";
         Expires = "Thu, 19 Nov 1981 08:52:00 GMT";
         "Keep-Alive" = "timeout=5, max=99";
         Pragma = "no-cache";
         Server = "Apache/2.4.10 (Win32) OpenSSL/1.0.1i PHP/5.5.19";
         "Www-Authenticate" = "Digest realm=\"Restricted area\",qop=\"auth\",nonce=\"5693a07f60c93\",opaque=\"cdce8a5c95a1427d74df7acbf41c9ce0\"";
 Blockquote     "X-Powered-By" = "PHP/5.5.19"; } },
</code></pre>