How to Set requestSerializer in Alamofire

I am currently working on a project in swift. I used Alamofire for REST API but to make it work I need to pass a parameter in requestSerializer.

In AFNETWORKING:

AFHTTPRequestOperationManager *manager = [AFHTTPRequestOperationManager manager];
manager.requestSerializer = [AFJSONRequestSerializer serializer];

But I can't find anything for Alamofire. I'm new to swift please help me out.

You can pass pass JSON data as encoding parameters, Encoding in Alamofire is equivalent to AFJSONRequestSerializer

request = Alamofire.request(.POST, webServicesURL, parameters: parameters, encoding: .JSON, headers: self.headers)

If you want to handle JSON data on response, just request

//This will give you response in JSON
request?.responseJSON { response in
        switch response.result
        {
        case .Success:
            success(response: response.result.value)
        case .Failure(let error):
            failure(error: error)
        }
    }

requestJSON is equivalent to AFJSONResponseSerializer in Alamofire

OR If you want to pass custom headers, pass a dictionary as

let headers = [
    "Content-Type": "application/json"
]
//Here we are passing the header in header parameter.
request = Alamofire.request(.POST, webServicesURL, parameters: parameters, encoding: .JSON, headers: self.headers)