title: swift.h Cannot Find Swift Class
body: <p>When I created a Swift class, Xcode will add this Swift class into swift.h. But nothing is added in swift.h, still.</p>
  
  <p>Normal swift.h:</p>
  
  <pre><code>SWIFT_CLASS("_TtC8facebook19swiftViewController")
  @interface swiftViewController : UIViewController
  - (void)viewDidLoad;
  - (void)didReceiveMemoryWarning;
  - (SWIFT_NULLABILITY(nonnull) instancetype)initWithNibName:(NSString * __nullable)nibNameOrNil bundle:(NSBundle * __nullable)nibBundleOrNil OBJC_DESIGNATED_INITIALIZER;
  - (SWIFT_NULLABILITY(nonnull) instancetype)initWithCoder:(NSCoder * __nonnull)aDecoder OBJC_DESIGNATED_INITIALIZER;
  </code></pre>
  
  <p>The aforementioned Swift class is, however, not in included my swift.h:</p>
  
  <pre><code>#pragma clang diagnostic ignored "-Wproperty-attribute-mismatch"
  #pragma clang diagnostic ignored "-Wduplicate-method-arg"
  #pragma clang diagnostic pop
  </code></pre>