when build my code then crash on  Alamofire.request(request as! URLRequestConvertible).responseJSON(). pls suggest how to fix this crash
let url         
        change let request = NSMutableURLRequest(url:url! as URL) to
    var request = URLRequest(url: NSURL(string: url)! as URL)
your code look like this:-
    let url = NSURL(string: "https://jsonplaceholder.typicode.com/users")
    var request = URLRequest(url: NSURL(string: url)! as URL)
    request.httpMethod = "GET"
    request.setValue("application/json", forHTTPHeaderField: "Content-Type")
    Alamofire.request(request as! URLRequestConvertible).responseJSON(){ response in
           switch response.result
           {
              case .success(let data):                
                 print(" i got my Data Yup",data)          
              case .failure(let error):
                 print(error)                                
            }
        }
You can also try with following syntax for request method:
Alamofire.request(strURL,method: .post, parameters: parameters as? [String : AnyObject], encoding: URLEncoding.default)
In Swift 3, all you have to do is to change NSMutableURLRequest to URLRequest and it will work. No need to cast. Also, set var so it can be swift mutable. :) Thanks, Markus for comment.