Snackbars in iOS.

class SnackBar: UIWindow {
    
    private let view = UIView()
    private let label = UILabel()
    
    private let aniDuration: TimeInterval = 0.3
    private let showDuration: TimeInterval = 2
    
    convenience init() {
        self.init(frame: UIScreen.main.bounds)
    }
    
    convenience init(bottom offset: CGFloat = 0) {
        self.init(frame: UIScreen.main.bounds)
        constraints.first(where: {$0.firstAttribute == .bottom})?.constant = -(16 + offset)
    }
    
    override init(frame: CGRect) {
        super.init(frame: frame)
        initView()
    }
    
    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        initView()
    }
    
    private func initView() {
        tag = "SnackBar".hashValue
        
        view.addGestureRecognizer(UITapGestureRecognizer(target: self, action: #selector(instantRemove)))
        view.translatesAutoresizingMaskIntoConstraints = false
        view.layer.cornerRadius = 10
        view.backgroundColor = "2BC3BA".color
        addSubview(view)
        
        NSLayoutConstraint.activate([
            view.heightAnchor.constraint(greaterThanOrEqualToConstant: 38),
            view.leadingAnchor.constraint(equalTo: safeAreaLayoutGuide.leadingAnchor, constant: 16),
            view.trailingAnchor.constraint(equalTo: safeAreaLayoutGuide.trailingAnchor, constant: -16),
            view.bottomAnchor.constraint(equalTo: safeAreaLayoutGuide.bottomAnchor, constant: -16)
            ])
        
        label.translatesAutoresizingMaskIntoConstraints = false
        label.font = UIFont.systemFont(ofSize: 12)
        label.textColor = .white
        label.numberOfLines = 2
        view.addSubview(label)
        
        NSLayoutConstraint.activate([
            label.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: 16),
            label.trailingAnchor.constraint(equalTo: view.trailingAnchor, constant: -16),
            label.topAnchor.constraint(equalTo: view.topAnchor, constant: 8),
            label.bottomAnchor.constraint(equalTo: view.bottomAnchor, constant: -8)
            ])
    }
    
    func show(_ text: String) {
        guard let snackBar = UIApplication.shared.windows.first(where: {$0 is SnackBar}), snackBar.isHidden else {return}
        
        alpha = 0
        isHidden = false
        label.text = text
        
        UIView.animate(withDuration: aniDuration, delay: 0, options: [.allowUserInteraction], animations: {
            self.alpha = 1
        })
        
        DispatchQueue.main.asyncAfter(deadline: .now() + aniDuration + showDuration) {
            guard self.alpha == 1 else {return}
            UIView.animate(withDuration: self.aniDuration, delay: 0, options: [.allowUserInteraction], animations: {
                self.alpha = 0
            }, completion: { _ in
                self.isHidden = true
            })
        }
    }
    
    @objc func instantRemove() {
        UIView.animate(withDuration: aniDuration, delay: 0, options: [.allowUserInteraction], animations: {
            self.alpha = 0
        }, completion: { _ in
            self.isHidden = true
        })
    }
    
    override func point(inside point: CGPoint, with event: UIEvent?) -> Bool {
        return view.frame.contains(point)
    }
    
}