Swift - Flip Animation

override func viewDidLoad() {
        super.viewDidLoad();
        
        view1 = self.autoLayoutPanelViewWithColor(UIColor(hex: 0xf6b37f, alpha: 1.0), title:"Music", logoImage:UIImage(named: "CD_grid@156px"), backViewBackgroundColor:UIColor(patternImage: UIImage(named: "bg1")), backViewTitle:"Music for better life")
        view2 = self.autoLayoutPanelViewWithColor(UIColor(hex: 0xf9a451, alpha: 1.0), title:"Relax", logoImage:UIImage(named: "coffee_grid@156px"), backViewBackgroundColor:UIColor(patternImage: UIImage(named: "bg2")), backViewTitle:"A cup of coffee for relax")
        view3 = self.autoLayoutPanelViewWithColor(UIColor(hex: 0xf78d60, alpha: 1.0), title:"Message", logoImage:UIImage(named: "message_grid@156px"), backViewBackgroundColor:UIColor(patternImage: UIImage(named: "bg3")), backViewTitle:"From:I have a dream")
        view4 = self.autoLayoutPanelViewWithColor(UIColor(hex: 0xfc7d38, alpha: 1.0), title:"Things", logoImage:UIImage(named: "things_grid@156px"), backViewBackgroundColor:UIColor(patternImage: UIImage(named: "bg4")), backViewTitle:"Do something valuable")
        view5 = self.autoLayoutPanelViewWithColor(UIColor(hex: 0xeb6100, alpha: 1.0), title:"Clock", logoImage:UIImage(named: "clock_grid@156px"), backViewBackgroundColor:UIColor(patternImage: UIImage(named: "bg5")), backViewTitle:"Time can't wait")
        view6 = self.autoLayoutPanelViewWithColor(UIColor(hex: 0xff5e33, alpha: 1.0), title:"Settings", logoImage:UIImage(named: "settings_grid@156px"), backViewBackgroundColor:UIColor(patternImage: UIImage(named: "bg6")), backViewTitle:"Keep in best condition")
        
        self.makeGlobalConstraintsToView(self.view, subviewArray: [view1,view2,view3,view4,view5,view6])
        
    }

link : https://github.com/JasonZengJ/GridPanelDemo