title: kGAIScreenName of Google Analytics for iOS v3 is undeclared?
body: <p>Today, I found GoogleAnalytics-iOS-SDK have new 3.0 version in Cocoapods. I upgraded and I try to modified the code of manual screen measurement as below:</p>
  
  <pre><code>id tracker = [[GAI sharedInstance] defaultTracker];
  [tracker set:kGAIScreenName value:@"Detail View"];
  [tracker send:[[GAIDictionaryBuilder createAppView] build]];
  </code></pre>
  
  <p>However, I always get error about kGAIScreenName is undeclared. Even I add GAIFields.h header, it still not work.</p>
  
  <p>What did I miss? </p>