It is saying that the result of call bind(to:) is unused because you are not attaching it to a disposable.

You need to create a disposeBag

In the scope of the class:

let disposeBag = DisposeBag()

And the after the .bind().disposed(by: disposeBag)

If not it wont be retained, the disposeBag retains all the subscriptions until it is disposed (and if you declare it in the class scope it will be disposed when the class is disposed)

Also Rx is a complex layer "over" swift, so when there is something wrong Xcode has many troubles to detect what is exactly the bug and it becomes crazy saying that there is a mistake but maybe not the right one (and it happens too when you are trying to use the autocompletable, Xcode sucks...) there is nothing you can do to fix it.