AFN

AFHTTPSessionManager *manager = [AFHTTPSessionManager manager];
manager.responseSerializer = [AFHTTPResponseSerializer serializer];
//manager.requestSerializer= [AFJSONRequestSerializer serializer];
//[manager.requestSerializer setValue:@"text/html" forHTTPHeaderField:@"Content-Type"];
manager.responseSerializer.acceptableContentTypes= [NSSet setWithObjects:@"application/json",@"text/json",@"text/javascript",@"text/html",@"image/png",@"image/jpeg",nil];