Instagram returning “Matching code was not found or was already used” when using OAuth

Question

I am trying to use the Instagram OAuth using the developer documentation at

https://www.instagram.com/developer/authentication/.

Step 1 and 2 a

Answer 1

I solved this by creating a service on the backend/server side that authorised the user.

My backend API is a ruby on rails app. Here is a code snippet to understand.

  def token
    @response = Instagram.get_access_token(params[:code], redirect_uri: mobile_token_url)
    instagram_user = InstagramUserCreator.new(user_params)
    if instagram_user.find_or_create
      redirect_to "taddarmobileapp://?token=#{instagram_user.user.token}"
    else
      redirect_to 'taddarmobileapp://'
    end
  end

I just store the token on the phone and use it to authorise the user to my backend API.