Regarding accessibilityTraits isToggle

Hello. In order to test how VoiceOver treat isToggle accessibilityTraits, I created simple code. I did not use Toggle View, because of test purposes. By the way, I have a question. Once I applied isToggle, VoiceOver just says swich button. Switch means is toggle, we have to provide state information such as on or off. So I thought that to provide state information, such as on or off, I should use accessibilityValue. But even if I applied accessibilityValue, VoiceOver does not read the value, just speak swich button. How to provide on or off state with accessibilityTraits isToggle? Thank you.