Update interop test service url to grpc-test.sandbox.googleapis.com.
diff --git a/examples/objective-c/auth_sample/MakeRPCViewController.m b/examples/objective-c/auth_sample/MakeRPCViewController.m
index 4fd23dc..6013186 100644
--- a/examples/objective-c/auth_sample/MakeRPCViewController.m
+++ b/examples/objective-c/auth_sample/MakeRPCViewController.m
@@ -39,7 +39,7 @@
NSString * const kTestScope = @"https://www.googleapis.com/auth/xapi.zoo";
-static NSString * const kTestHostAddress = @"grpc-test.sandbox.google.com";
+static NSString * const kTestHostAddress = @"grpc-test.sandbox.googleapis.com";
// Category for RPC errors to create the descriptions as we want them to appear on our view.
@interface NSError (AuthSample)