title: Adding App Events in iOS app produces undeclared identifier 'AppEvent'
body: <p>I am trying to add facebook app events, and I installed FacebookSDK. Then I have next code:</p>
  
  <pre><code>import FacebookCore
  
  static func logViewContentEvent(contentType : String, contentData : String, contentId : String, currency : String, price : Double) {
          let params : AppEvent.ParametersDictionary = [
              .contentType : contentType,
              .content : contentData,
              .contentId : contentId,
              .currency : currency
          ]
          let event = AppEvent(name: .viewedContent, parameters: params, valueToSum: price)
          AppEventsLogger.log(event)
      }
  </code></pre>
  
  <p>But I get error from the title. What I am doing wrong, and why this type is missing?</p>