title: iOS UIView adding and removing subviews throughout the code
body: <p>I have a blue line in my app that displays an artificial horizon.
  I want to be able to display and remove it at different parts of the code (.m).
  Can I declare it (lineViewHorizon) universally. </p>
  
  <p>At present I can make it appear/disappear only within the same section/method of code.</p>
  
  <p>I presume this can be done?</p>
  
  <pre><code>UIView *lineViewHorizon = [[UIView alloc] initWithFrame:CGRectMake(0, pageTopMargin+inthorizon, self.view.bounds.size.width, 2)];
  lineViewHorizon.backgroundColor = [UIColor blueColor];
  [self.view addSubview:lineViewHorizon];
  [lineViewHorizon removeFromSuperview];
  </code></pre>