diff --git a/.DS_Store b/.DS_Store
index ec9f6f7..3eb0732 100644
Binary files a/.DS_Store and b/.DS_Store differ
diff --git a/objc-interpolate-001-prework-ios b/objc-interpolate-001-prework-ios
new file mode 160000
index 0000000..242b67e
--- /dev/null
+++ b/objc-interpolate-001-prework-ios
@@ -0,0 +1 @@
+Subproject commit 242b67e0103cc708a386fa9d204351916621942a
diff --git a/your-first-NSLog/FISAppDelegate.m b/your-first-NSLog/FISAppDelegate.m
index 757a006..bebac9a 100644
--- a/your-first-NSLog/FISAppDelegate.m
+++ b/your-first-NSLog/FISAppDelegate.m
@@ -13,6 +13,9 @@ - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(
      */
     
     // do not alter
+    
+    NSLog(@"Hello World!");
+    
     return YES;  //
 }   ///////////////