title: CodeIgniter-Checking session variable is already set or not when clicking each link or reloading page
body: <p>I have a controller named admin,and all functions in the controller can be used if the session variable is set,so what are the best ways to check if the session is set ,when clicking each link in the page or reloading the pages...</p>
  
  <blockquote>
    <p>for example: if i open my admin home page in multiple tabs in a
    browser and sign off from first tab, bt after that in the second tab
    all links a working properly</p>
  </blockquote>
  
  <p>so i want to check if the session is set or not...</p>
  
  <p>Thanks!</p>