title: iOS and xcode: how to create a modal segue to a special view only the first time the app is used
body: <p>I want to make a "terms and conditions" screen that pops up the very first time that app is opened. On this view I would add a button that says "agree," and upon clicking it the code would execute:</p>
  
  <pre><code>[self dismissViewControllerAnimated:YES completion:nil];
  </code></pre>
  
  <p>...and would go to the first view of the app.</p>
  
  <p>I am currently using a Tab Bar Controller that has 4 ViewControllers. So basically, I just need to have some method in viewWillAppear on my first ViewController that checks for an NSUserDefault key:value. The first time the app opens, it will be zero. After they click agree, I'll set it to 1 and the bit of code would never execute again.</p>
  
  <p>Can you please offer some code to accomplish the task of routing the view from the firstViewController's view to this alternate view controller upon loading the app?</p>
  
  <p>Thanks!</p>