Simple iOS Toast

UIWindowExt.swift

var ak_toast_view_tag = 595;
var ak_toast_label_tag = 585;

extension UIWindow{
    func showToast(text: String){
        let v = getToastView();
        if v.superview != nil{
            v.removeFromSuperview();
        }
        let label = getToastLabel();
        if label.superview == nil{
            v.addSubview(label);
        }
        let labelOldFrame = label.frame;
        label.text = text;
        label.sizeToFit();
        if labelOldFrame.width > label.frame.width{
            label.frame.size.width = labelOldFrame.width;
        }
        v.frame.size.height = label.frame.height + 20;
        v.frame.origin.y = screenSize.height - v.frame.height - 55;
        v.frame.origin.x = (screenSize.width - v.frame.width)/2;
        v.alpha = 0;
        self.addSubview(v);
        UIView.animateWithDuration(0.4, animations: { 
            v.alpha = 0.8;
            }) { (doned) in
                UIView.animateWithDuration(0.4, delay: 2.0, options: UIViewAnimationOptions.CurveEaseInOut, animations: {
                    v.alpha = 0;
                    }, completion: { (doned2) in
                        v.removeFromSuperview();
                })
        }
    }
    
    func getToastView()->UIView{
        var v = self.viewWithTag(ak_toast_view_tag);
        if v == nil{
            v = UIView();
        }
        v!.tag = ak_toast_view_tag;
        v!.frame = CGRectMake(10, screenSize.height - 80, screenSize.width - 40, 40);
        v!.backgroundColor = UIColor.blackColor().colorWithAlphaComponent(70);
        v!.layer.cornerRadius = 20;
        v!.clipsToBounds = true;
        return v!;
    }
    
    func getToastLabel()->UILabel{
        var label: UILabel? = self.getToastView().viewWithTag(ak_toast_label_tag) as? UILabel;
        if label == nil{
            label = UILabel();
        }
        label!.tag = ak_toast_label_tag;
        label!.textAlignment = .Center;
        label!.numberOfLines = 0;
        label!.font = UIFont.systemFontOfSize(14);
        label!.frame = CGRectMake(5, 10, getToastView().frame.width - 10, 20);
        label!.textColor = UIColor.whiteColor();
        return label!;
    }
}

ViewController.swift

class ViewController: UIViewController{
  func viewDidLoad(){
    let appDelegate = UIApplication.sharedApplication().delegate as? AppDelegate
    appDelegate.window?.showToast("Hello world");
  }
}