(Swift 3,4,5...) Twitter API v2 - Get OAuth2 Access Token

See more Twitter API v2 Examples

Demonstrates how to get a Twitter API v2 OAuth2 access token from a desktop application or script.

For more information, see https://developer.twitter.com/en/docs/authentication/oauth-2-0/user-access-token

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func chilkatTest() {
    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    let oauth2 = CkoOAuth2()!
    var success: Bool

    // This should be the port in the localhost callback URI for your App (defined in the Twitter Developer Portal)
    // The Callback URI / Redirect URL should be "http://localhost:3017/" if the port number is 3017.
    oauth2.listenPort = 3017

    oauth2.authorizationEndpoint = "https://twitter.com/i/oauth2/authorize"
    oauth2.tokenEndpoint = "https://api.twitter.com/2/oauth2/token"

    // Replace these with actual values.
    oauth2.clientId = "CLIENT_ID"
    oauth2.clientSecret = "CLIENT_SECRET"

    oauth2.scope = "tweet.read users.read follows.read follows.write"

    oauth2.addAuthQueryParam("offline.access", value: "")
    oauth2.addAuthQueryParam("state", value: "state")
    oauth2.codeChallenge = true
    oauth2.codeChallengeMethod = "plain"
    oauth2.useBasicAuth = true

    // Begin the OAuth2 three-legged flow.  This returns a URL that should be loaded in a browser.
    var url: String? = oauth2.start()
    if oauth2.lastMethodSuccess != true {
        print("\(oauth2.lastErrorText!)")
        return
    }

    print("\(url!)")

    // At this point, your application should load the URL in a browser.
    // For example, 
    // in C#: System.Diagnostics.Process.Start(url);
    // in Java: Desktop.getDesktop().browse(new URI(url));
    // in VBScript: Set wsh=WScript.CreateObject("WScript.Shell")
    //              wsh.Run url
    // in Xojo: ShowURL(url)  (see http://docs.xojo.com/index.php/ShowURL)
    // in Dataflex: Runprogram Background "c:\Program Files\Internet Explorer\iexplore.exe" sUrl        
    // The Microsoft account owner would interactively accept or deny the authorization request.

    // Add the code to load the url in a web browser here...
    // Add the code to load the url in a web browser here...
    // Add the code to load the url in a web browser here...

    // Now wait for the authorization.
    // We'll wait for a max of 60 seconds.
    var numMsWaited: Int = 0
    while (numMsWaited < 60000) && (oauth2.authFlowState.intValue < 3) {
        oauth2.sleepMs(100)
        numMsWaited = numMsWaited + 100
    }

    // If there was no response from the browser within 60 seconds, then 
    // the AuthFlowState will be equal to 1 or 2.
    // 1: Waiting for Redirect. The OAuth2 background thread is waiting to receive the redirect HTTP request from the browser.
    // 2: Waiting for Final Response. The OAuth2 background thread is waiting for the final access token response.
    // In that case, cancel the background task started in the call to StartAuth.
    if oauth2.authFlowState.intValue < 3 {
        oauth2.cancel()
        print("No response from the browser!")
        return
    }

    // Check the AuthFlowState to see if authorization was granted, denied, or if some error occurred
    // The possible AuthFlowState values are:
    // 3: Completed with Success. The OAuth2 flow has completed, the background thread exited, and the successful JSON response is available in AccessTokenResponse property.
    // 4: Completed with Access Denied. The OAuth2 flow has completed, the background thread exited, and the error JSON is available in AccessTokenResponse property.
    // 5: Failed Prior to Completion. The OAuth2 flow failed to complete, the background thread exited, and the error information is available in the FailureInfo property.
    if oauth2.authFlowState.intValue == 5 {
        print("OAuth2 failed to complete.")
        print("\(oauth2.failureInfo!)")
        return
    }

    if oauth2.authFlowState.intValue == 4 {
        print("OAuth2 authorization was denied.")
        print("\(oauth2.accessTokenResponse!)")
        return
    }

    if oauth2.authFlowState.intValue != 3 {
        print("Unexpected AuthFlowState:\(oauth2.authFlowState.intValue)")
        return
    }

    print("OAuth2 authorization granted!")
    print("Access Token = \(oauth2.accessToken!)")

    // Get the full JSON response:
    let json = CkoJsonObject()!
    json.load(oauth2.accessTokenResponse)
    json.emitCompact = false

    // The JSON response looks like this:

    // {
    //   "token_type": "bearer",
    //   "expires_in": 7200,
    //   "access_token": "NnAfRUxCVWhLNDB3MFRvd25yQlNnelRZY1F1WkFlQqVfNXYwOEVobVNqR0VfOjf2NTg4NDk0MjMxnzE6MTowOmF2OjE",
    //   "scope": "users.read follows.read tweet.read follows.write"
    // }

    print("\(json.emit()!)")

    // Save the JSON to a file for future requests.
    let fac = CkoFileAccess()!
    fac.writeEntireTextFile("qa_data/tokens/twitter_v2_oauth2.json", fileData: json.emit(), charset: "utf-8", includePreamble: false)

}