title: Failed to initialize Firebase
body: <p>I am developing an iOS project (with xcode 8 &amp; swift 3). I have installed firebase pod through cocoapod. This is my pod:</p>
  
  <pre><code>target 'myApp' do
     pod 'Firebase', '~&gt; 3.9'
  end
  </code></pre>
  
  <p>Then I open myApp.xcworkspace file, the project is opened in Xcode.</p>
  
  <p>Then I try to initialize a firebase instance by:</p>
  
  <pre><code>let BASE_URL = "https://myapp-35211.firebaseio.com/"
  // ERROR: Cannot call value of non-function type 'module&lt;Firebase&gt;'
  let firebase = Firebase(url: "\(BASE_URL)")
  </code></pre>
  
  <p>(I have <code>import Firebase</code>)</p>
  
  <p>I am trying to use firebase database.</p>
  
  <p>Why I get the above error?</p>
  
  <p><strong>====== UPDATE =======</strong></p>
  
  <p>OK, I followed the steps to initialize Firebase (add my project in Firebase, download the GoogleService-Info.plist &amp; use <code>FIRApp.configure()</code>, etc). Now I get this error:</p>
  
  <p><a href="https://i.stack.imgur.com/CjObZ.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/CjObZ.png" alt="enter image description here"></a></p>
  
  <p>Why?</p>
  
  <p>My Podfile is like this:</p>
  
  <pre><code>target 'myApp' do
     pod 'Firebase', '~&gt; 3.9'
  end
  </code></pre>
  
  <p>Does it mean this pod doesn't include <code>Firebase/Database</code> ???</p>
  
  <p><strong>===== UPDATE AGAIN =====</strong></p>
  
  <p>OK, add <code>'Firebase/Database'</code> to <strong>Podfile</strong> solved the above issue, but why <code>'Firebase'</code> pod doesn't include <code>Firebase/Database</code>? Isn't it a subset of <code>'Firebase'</code> pod?</p>