I want to get a display/hide status of the iOS keyboard.

// Prepare variables
varisShown=false

// Configure monitoring in viewDidLoad, etc.
NotificationCenter.default.addObserver(self,selector:#selector(keyboardDidAppear), name:UIResponder.keyboardDidShowNotification, object:nil)
NotificationCenter.default.addObserver(self,selector:#selector(keyboardDidDisappear), name:UIResponder.keyboardDidHideNotification, object:nil)

switch flags
@objc func keyboardDidAppear(){
    isShown = true
}
@objc func keyboardDidDisappear(){
    isShown = false
}

if isShown{
    // When the keyboard is displayed
} else{
    // the time when a person is hiding
}