Ideally, there would be a way to wait for the engine to finish setting up. E.g., the following code is racy (and consistently is a no-op for me on a simulator):

 FlutterEngine* engine = [[FlutterEngine alloc] initWithName:@"PlatformViewTest" project:nil];
    [engine runWithEntrypoint:nil];
  
    [engine.binaryMessenger sendOnChannel:@"set_scenario" message:[@"text_platform_view" dataUsingEncoding:NSUTF8StringEncoding]];

Adding a sleep makes things "work".

Ideally, this message would get delivered once the engine was ready.

/cc @jmagman @xster @chinmaygarde @gaaclarke