Swift Gmail API: Try to send message gives error -1001

Question

I'm trying to send a gmail message in Swift using the GoogleAPIClientForREST and GTMOAuth2 libraries but I'm getting the aforementioned error.

Here's my code:

    let message = GTLRGmail_Message()
    message.raw = "test"
    let query = GTLRGmailQuery_UsersMessagesSend.query(withObject: message, userId: "[email protected]", uploadParameters: nil)
    let gmailService = GTLRGmailService()
    let auth = GTMOAuth2Authentication()
    auth.clientID = gmailClientID
    gmailService.authorizer = auth
    gmailService.executeQuery(query) { ticket, object, error in
        print(ticket)
        print(object)
        print(error)
    }

and here's the error:

Optional(Error Domain=com.google.GTMOAuth2 Code=-1001 "(null)" UserInfo={request=<NSMutableURLRequest: 0x600000016ed0> { URL: https://www.googleapis.com/gmail/v1/users/example%40gmail.com/messages/send?prettyPrint=false }})

Notes:

• I used "[email protected]" for sake of asking the question, I'm using a real email in my app.
• I followed all the basic steps in Google's tutorial

Answer 1

Make sure that you've integrated GTMOAuth2 properly into your app by following this tutorial. Be sure to register the Platform as Other and NOT iOS otherwise you'll get "invalid_client" error when authenticating.

You may also check the given solution on this thread.