Updated user agent to be a host-level setting
diff --git a/examples/objective-c/helloworld/main.m b/examples/objective-c/helloworld/main.m
index b673808..755dce3 100644
--- a/examples/objective-c/helloworld/main.m
+++ b/examples/objective-c/helloworld/main.m
@@ -43,7 +43,7 @@
 int main(int argc, char * argv[]) {
   @autoreleasepool {
     [GRPCCall useInsecureConnectionsForHost:kHostAddress];
-    [GRPCCall setUserAgentPrefix:@"HelloWorld/1.0"];
+    [GRPCCall setUserAgentPrefix:@"HelloWorld/1.0" forHost:kHostAddress];
 
     HLWGreeter *client = [[HLWGreeter alloc] initWithHost:kHostAddress];