title: Firebase InstanceId unresolved identifier swift4
body: <p>I have recently updated My SWIFT applications pod file, And because of that firebase version is now updated to a 5.2.
  Which now gives me following error while getting a device instance id.</p>
  
  <pre><code>let tokenId = InstanceID.instanceID().token()
  </code></pre>
  
  <p>error: <strong>Use of unresolved identifier 'InstanceID'</strong></p>
  
  <p>Previously this code was working fine and I was getting Application's Instance Id.</p>
  
  <p>Following is content of my pod file.</p>
  
  <pre><code>   # Uncomment the next line to define a global platform for your project
  # platform :ios, '11.2'
  
  target 'FirebaseChat' do
    # Comment the next line if you're not using Swift and don't want to use dynamic frameworks
    use_frameworks!
  
    # Pods for FirebaseChat
  
  pod 'Firebase/Database'
  pod 'Firebase/Auth'
  pod 'Firebase/Storage'
  pod 'UnderLineTextField', '~&gt; 2.0'
  pod 'Alamofire'
  pod 'TCPickerView'
  pod 'Toast-Swift', '~&gt; 3.0.1'
  pod 'IQKeyboardManagerSwift'
  end
  </code></pre>
  
  <p>Any suggestions will be helpful.
  Thank You.</p>