title: Xcode Project won't run on iOS Device
body: <p>Xcode gives me this message every-time I try running my app on my iPhone. (Works fine on the simulator.) (And this occurs in every project I have.) (I also just downloaded Xcode again.) </p>
  
  <p>This is the message I get. </p>
  
  <pre><code>App Installation Failed.
  Unknown Error Occurred.
  </code></pre>
  
  <p>How do I fix this error?</p>