bachand · September 10, 2015 20:46 · Sep 10, 2015
diff --git a/MasteringFocusExample5.swift b/MasteringFocusExample5.swift
@@ -0,0 +1,24 @@
+class ActionHeroesView: UIView {
+  let stalloneButton: UIButton
+  let vanDammeButton: UIButton
+
+  // ...
+
+  override func didUpdateFocusInContext(context: UIFocusUpdateContext, withAnimationCoordinator coordinator: UIFocusAnimationCoordinator) {
+    super.didUpdateFocusInContext(context, withAnimationCoordinator: coordinator)
+
+    // we'll center Stallone when neither is in focus since he's a bigger deal
+    let vanDammeFocused = (context.nextFocusedView == vanDammeButton)
+
+    layoutIfNeeded()
+
+    coordinator.addCoordinatedAnimations({
+        self.stalloneCenterXConstraint.active = !vanDammeFocused
+        self.vanDammeCenterXConstraint.active = vanDammeFocused
+
+        self.layoutIfNeeded()
+      },
+      completion: nil
+    )
+  }
+}