I want to implement grey foregound with instruciton in my ios App

Question

I want to implement something like this in my ios app :

I want a transparent foreground with a warning message similar to "please enable Bluetooth to continue using this app" in my ios App. How can I implement a similar kind of behavior in my app?

Answer 1

 var vc: BannerViewController!

    func addBanner(){
        vc = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(identifier: "BannerViewController")
        UIApplication.shared.keyWindow?.addSubview(vc.view)
        let sv = vc.view.superview!
        vc.view.translatesAutoresizingMaskIntoConstraints = false
        let constrainst = [
            vc.view.topAnchor.constraint(equalTo: sv.topAnchor),
            vc.view.leadingAnchor.constraint(equalTo: sv.leadingAnchor),
            vc.view.bottomAnchor.constraint(equalTo: sv.bottomAnchor),
            vc.view.trailingAnchor.constraint(equalTo: sv.trailingAnchor)
        ]
        vc.view.isUserInteractionEnabled = true
        vc.view.backgroundColor = UIColor.red
        NSLayoutConstraint.activate(constrainst)
    }

    func removeBanner(){
        vc.view.removeFromSuperview()
        vc = nil
    }

The above functions can help you achieve what you want. basically design your banner in storyboard. then have a variable at class level. when the bluetooth is turned off in that callback, call the addBanner function and in the callback function of bluetooth turned on call the removeBanner function.