React Native & TypeScript : Property 'focus' does not exist on type 'RefObject'

That's what I am doing:

  declare passCodeInput:  React.RefObject<TextInput>;

But here's an issue that I am getting while trying to call focus method:

setTimeout(() => this.passCodeInput.focus());

I call focus on current, like, this.passCodeInput.current!.focus()) but this won't work in my case.