swift/Alamofire/API token/ Missing required parameter: grant_type

I'm attempting to create TwitterSearcher.

My Conditions are

• Using app-only authentication
• standard search API
• Using Alamofire, SwiftyJSON

As some of you know, you need to get a token in order to access Twitter before searching for tweets.

I'm pretty new to using API itself but I barely implemented some code. However, I came across an error response below on the way to get a token.

{
  "errors" : [
    {
      "code" : 170,
      "label" : "forbidden_missing_parameter",
      "message" : "Missing required parameter: grant_type"
    }
  ]
}

I have already tried some ways referring to other articles, let's say

• changing param to ["payload" : "grant_type=client_credentials"]
• eliminate "content_type" from Header

Although I haven't grabbed the meanings of these two, the error is still going on.

import Foundation
import Alamofire
import SwiftyJSON

protocol SearchUserApi {
    func getToken()
    func getTweets(content: String)
}

class APIOperator: SearchUserApi {
    
     var accessToken: String?
     let tokenApi = "https://api.twitter.com/oauth2/token"
     let api = "https://api.twitter.com/1.1/search/tweets.json"
     let consumerKey = "---"
     let consumerSecret = "---"
    

    
    func getToken() {
        let credentials = "\(consumerKey):\(consumerSecret)".data(using: String.Encoding.utf8)!.base64EncodedString(options: NSData.Base64EncodingOptions(rawValue: 0))
        let headers = [
            "Authorization" : "Basic \(credentials)",
            "Content-Type": "application/x-www-form-urlencoded;charset=UTF-8"
        ]
        let params: [String : AnyObject] = ["grant_type": "client_credentials" as AnyObject]
        
        
        Alamofire.request(
            tokenApi,
            method: .post,
            parameters: params,
            encoding: JSONEncoding.default,
            headers: headers
            )
            .responseJSON { (response) in
                guard let object = response.result.value else {
                    print("Getting token is failed")
                    return
                }
                let json = JSON(object)
                print(json)
        }
        
        
    }
    
    func getTweets(content: String) {
       print("not yet")
    }  
}

Hope you will help me out.

You can try with URLEncoding.httpBody instead of JSONEncoding.default

OR

Alamofire directly support Basic auth

see this

https://github.com/Alamofire/Alamofire/blob/master/Documentation/Usage.md#authentication

Here is sample code from docs

let user = "user"
let password = "password"

let credential = URLCredential(user: user, password: password, persistence: .forSession)

Alamofire.request("https://httpbin.org/basic-auth/\(user)/\(password)")
    .authenticate(usingCredential: credential)
    .responseJSON { response in
        debugPrint(response)
}

and use authorizationHeader as request header in alamofire

Hope it is helpful