         textFieldContainerView.addSubview(textField)
     }
     
-    public func isAlert() -> Bool { return preferredStyle == .Alert }
+    open func isAlert() -> Bool { return preferredStyle == .alert }
     
     // MARK: UITextFieldDelegate Methods
     
-    public func textFieldShouldReturn(textField: UITextField) -> Bool {
-        if (textField.canResignFirstResponder()) {
+    open func textFieldShouldReturn(_ textField: UITextField) -> Bool {
+        if (textField.canResignFirstResponder) {
             textField.resignFirstResponder()
-            self.dismissViewControllerAnimated(true, completion: nil)
+            self.dismiss(animated: true, completion: nil)
         }
         return true
     }
     
     // MARK: UIViewControllerTransitioningDelegate Methods
-    public
-    func animationControllerForPresentedController(presented: UIViewController, presentingController presenting: UIViewController, sourceController source: UIViewController) -> UIViewControllerAnimatedTransitioning? {
+    open
+    func animationController(forPresented presented: UIViewController, presenting: UIViewController, source: UIViewController) -> UIViewControllerAnimatedTransitioning? {
         layoutView(presenting)
         return DOAlertAnimation(isPresenting: true)
     }
     
-    public func animationControllerForDismissedController(dismissed: UIViewController) -> UIViewControllerAnimatedTransitioning? {
+    open func animationController(forDismissed dismissed: UIViewController) -> UIViewControllerAnimatedTransitioning? {
         return DOAlertAnimation(isPresenting: false)
     }
 }


// MARK: DOAlertAnimation Class

public class DOAlertAnimation : NSObject, UIViewControllerAnimatedTransitioning {
    
    let isPresenting: Bool
    

        buttonContainer.translatesAutoresizingMaskIntoConstraints = false
        
        // self.view
        let overlayViewTopSpaceConstraint = NSLayoutConstraint(item: overlayView, attribute: .top, relatedBy: .equal, toItem: self.view, attribute: .top, multiplier: 1.0, constant: 0.0)
        let overlayViewRightSpaceConstraint = NSLayoutConstraint(item: overlayView, attribute: .right, relatedBy: .equal, toItem: self.view, attribute: .right, multiplier: 1.0, constant: 0.0)
        let overlayViewLeftSpaceConstraint = NSLayoutConstraint(item: overlayView, attribute: .left, relatedBy: .equal, toItem: self.view, attribute: .left, multiplier: 1.0, constant: 0.0)
        let overlayViewBottomSpaceConstraint = NSLayoutConstraint(item: overlayView, attribute: .bottom, relatedBy: .equal, toItem: self.view, attribute: .bottom, multiplier: 1.0, constant: 0.0)
        let containerViewTopSpaceConstraint = NSLayoutConstraint(item: containerView, attribute: .top, relatedBy: .equal, toItem: self.view, attribute: .top, multiplier: 1.0, constant: 0.0)
        let containerViewRightSpaceConstraint = NSLayoutConstraint(item: containerView, attribute: .right, relatedBy: .equal, toItem: self.view, attribute: .right, multiplier: 1.0, constant: 0.0)
        let containerViewLeftSpaceConstraint = NSLayoutConstraint(item: containerView, attribute: .left, relatedBy: .equal, toItem: self.view, attribute: .left, multiplier: 1.0, constant: 0.0)
        containerViewBottomSpaceConstraint = NSLayoutConstraint(item: containerView, attribute: .bottom, relatedBy: .equal, toItem: self.view, attribute: .bottom, multiplier: 1.0, constant: 0.0)
        self.view.addConstraints([overlayViewTopSpaceConstraint, overlayViewRightSpaceConstraint, overlayViewLeftSpaceConstraint, overlayViewBottomSpaceConstraint, containerViewTopSpaceConstraint, containerViewRightSpaceConstraint, containerViewLeftSpaceConstraint, containerViewBottomSpaceConstraint!])
        
        if (isAlert()) {
            // ContainerView
            let alertViewCenterXConstraint = NSLayoutConstraint(item: alertView, attribute: .centerX, relatedBy: .equal, toItem: containerView, attribute: .centerX, multiplier: 1.0, constant: 0.0)
            let alertViewCenterYConstraint = NSLayoutConstraint(item: alertView, attribute: .centerY, relatedBy: .equal, toItem: containerView, attribute: .centerY, multiplier: 1.0, constant: 0.0)
            containerView.addConstraints([alertViewCenterXConstraint, alertViewCenterYConstraint])
            
            // AlertView
            let alertViewWidthConstraint = NSLayoutConstraint(item: alertView, attribute: .width, relatedBy: .equal, toItem: nil, attribute: .width, multiplier: 1.0, constant: alertViewWidth)
            alertViewHeightConstraint = NSLayoutConstraint(item: alertView, attribute: .height, relatedBy: .equal, toItem: nil, attribute: .height, multiplier: 1.0, constant: 1000.0)
            alertView.addConstraints([alertViewWidthConstraint, alertViewHeightConstraint!])
            
        } else {
            // ContainerView
            let alertViewCenterXConstraint = NSLayoutConstraint(item: alertView, attribute: .centerX, relatedBy: .equal, toItem: containerView, attribute: .centerX, multiplier: 1.0, constant: 0.0)
            let alertViewBottomSpaceConstraint = NSLayoutConstraint(item: alertView, attribute: .bottom, relatedBy: .equal, toItem: containerView, attribute: .bottom, multiplier: 1.0, constant: actionSheetBounceHeight)
            let alertViewWidthConstraint = NSLayoutConstraint(item: alertView, attribute: .width, relatedBy: .equal, toItem: containerView, attribute: .width, multiplier: 1.0, constant: 0.0)
            containerView.addConstraints([alertViewCenterXConstraint, alertViewBottomSpaceConstraint, alertViewWidthConstraint])
            
            // AlertView
            alertViewHeightConstraint = NSLayoutConstraint(item: alertView, attribute: .height, relatedBy: .equal, toItem: nil, attribute: .height, multiplier: 1.0, constant: 1000.0)
            alertView.addConstraint(alertViewHeightConstraint!)
        }
        
        // AlertView
        let textAreaScrollViewTopSpaceConstraint = NSLayoutConstraint(item: textAreaScrollView, attribute: .top, relatedBy: .equal, toItem: alertView, attribute: .top, multiplier: 1.0, constant: 0.0)
        let textAreaScrollViewRightSpaceConstraint = NSLayoutConstraint(item: textAreaScrollView, attribute: .right, relatedBy: .equal, toItem: alertView, attribute: .right, multiplier: 1.0, constant: 0.0)
        let textAreaScrollViewLeftSpaceConstraint = NSLayoutConstraint(item: textAreaScrollView, attribute: .left, relatedBy: .equal, toItem: alertView, attribute: .left, multiplier: 1.0, constant: 0.0)
        let textAreaScrollViewBottomSpaceConstraint = NSLayoutConstraint(item: textAreaScrollView, attribute: .bottom, relatedBy: .equal, toItem: buttonAreaScrollView, attribute: .top, multiplier: 1.0, constant: 0.0)
        let buttonAreaScrollViewRightSpaceConstraint = NSLayoutConstraint(item: buttonAreaScrollView, attribute: .right, relatedBy: .equal, toItem: alertView, attribute: .right, multiplier: 1.0, constant: 0.0)
        let buttonAreaScrollViewLeftSpaceConstraint = NSLayoutConstraint(item: buttonAreaScrollView, attribute: .left, relatedBy: .equal, toItem: alertView, attribute: .left, multiplier: 1.0, constant: 0.0)
        let buttonAreaScrollViewBottomSpaceConstraint = NSLayoutConstraint(item: buttonAreaScrollView, attribute: .bottom, relatedBy: .equal, toItem: alertView, attribute: .bottom, multiplier: 1.0, constant: isAlert() ? 0.0 : -actionSheetBounceHeight)
        alertView.addConstraints([textAreaScrollViewTopSpaceConstraint, textAreaScrollViewRightSpaceConstraint, textAreaScrollViewLeftSpaceConstraint, textAreaScrollViewBottomSpaceConstraint, buttonAreaScrollViewRightSpaceConstraint, buttonAreaScrollViewLeftSpaceConstraint, buttonAreaScrollViewBottomSpaceConstraint])
        
        // TextAreaScrollView
        let textAreaViewTopSpaceConstraint = NSLayoutConstraint(item: textAreaView, attribute: .top, relatedBy: .equal, toItem: textAreaScrollView, attribute: .top, multiplier: 1.0, constant: 0.0)
        let textAreaViewRightSpaceConstraint = NSLayoutConstraint(item: textAreaView, attribute: .right, relatedBy: .equal, toItem: textAreaScrollView, attribute: .right, multiplier: 1.0, constant: 0.0)
        let textAreaViewLeftSpaceConstraint = NSLayoutConstraint(item: textAreaView, attribute: .left, relatedBy: .equal, toItem: textAreaScrollView, attribute: .left, multiplier: 1.0, constant: 0.0)
        let textAreaViewBottomSpaceConstraint = NSLayoutConstraint(item: textAreaView, attribute: .bottom, relatedBy: .equal, toItem: textAreaScrollView, attribute: .bottom, multiplier: 1.0, constant: 0.0)
        let textAreaViewWidthConstraint = NSLayoutConstraint(item: textAreaView, attribute: .width, relatedBy: .equal, toItem: textAreaScrollView, attribute: .width, multiplier: 1.0, constant: 0.0)
        textAreaScrollView.addConstraints([textAreaViewTopSpaceConstraint, textAreaViewRightSpaceConstraint, textAreaViewLeftSpaceConstraint, textAreaViewBottomSpaceConstraint, textAreaViewWidthConstraint])
        
        // TextArea
        let textAreaViewHeightConstraint = NSLayoutConstraint(item: textAreaView, attribute: .height, relatedBy: .equal, toItem: textContainer, attribute: .height, multiplier: 1.0, constant: 0.0)
        let textContainerTopSpaceConstraint = NSLayoutConstraint(item: textContainer, attribute: .top, relatedBy: .equal, toItem: textAreaView, attribute: .top, multiplier: 1.0, constant: 0.0)
        let textContainerCenterXConstraint = NSLayoutConstraint(item: textContainer, attribute: .centerX, relatedBy: .equal, toItem: textAreaView, attribute: .centerX, multiplier: 1.0, constant: 0.0)
        textAreaView.addConstraints([textAreaViewHeightConstraint, textContainerTopSpaceConstraint, textContainerCenterXConstraint])
        
        // TextContainer
        let textContainerWidthConstraint = NSLayoutConstraint(item: textContainer, attribute: .width, relatedBy: .equal, toItem: nil, attribute: .width, multiplier: 1.0, constant: innerContentWidth)
        textContainerHeightConstraint = NSLayoutConstraint(item: textContainer, attribute: .height, relatedBy: .equal, toItem: nil, attribute: .height, multiplier: 1.0, constant: 0.0)
        textContainer.addConstraints([textContainerWidthConstraint, textContainerHeightConstraint!])
        
        // ButtonAreaScrollView
        buttonAreaScrollViewHeightConstraint = NSLayoutConstraint(item: buttonAreaScrollView, attribute: .height, relatedBy: .equal, toItem: nil, attribute: .height, multiplier: 1.0, constant: 0.0)
        let buttonAreaViewTopSpaceConstraint = NSLayoutConstraint(item: buttonAreaView, attribute: .top, relatedBy: .equal, toItem: buttonAreaScrollView, attribute: .top, multiplier: 1.0, constant: 0.0)
        let buttonAreaViewRightSpaceConstraint = NSLayoutConstraint(item: buttonAreaView, attribute: .right, relatedBy: .equal, toItem: buttonAreaScrollView, attribute: .right, multiplier: 1.0, constant: 0.0)
        let buttonAreaViewLeftSpaceConstraint = NSLayoutConstraint(item: buttonAreaView, attribute: .left, relatedBy: .equal, toItem: buttonAreaScrollView, attribute: .left, multiplier: 1.0, constant: 0.0)
        let buttonAreaViewBottomSpaceConstraint = NSLayoutConstraint(item: buttonAreaView, attribute: .bottom, relatedBy: .equal, toItem: buttonAreaScrollView, attribute: .bottom, multiplier: 1.0, constant: 0.0)
        let buttonAreaViewWidthConstraint = NSLayoutConstraint(item: buttonAreaView, attribute: .width, relatedBy: .equal, toItem: buttonAreaScrollView, attribute: .width, multiplier: 1.0, constant: 0.0)
        buttonAreaScrollView.addConstraints([buttonAreaScrollViewHeightConstraint!, buttonAreaViewTopSpaceConstraint, buttonAreaViewRightSpaceConstraint, buttonAreaViewLeftSpaceConstraint, buttonAreaViewBottomSpaceConstraint, buttonAreaViewWidthConstraint])
        
        // ButtonArea
        let buttonAreaViewHeightConstraint = NSLayoutConstraint(item: buttonAreaView, attribute: .height, relatedBy: .equal, toItem: buttonContainer, attribute: .height, multiplier: 1.0, constant: 0.0)
        let buttonContainerTopSpaceConstraint = NSLayoutConstraint(item: buttonContainer, attribute: .top, relatedBy: .equal, toItem: buttonAreaView, attribute: .top, multiplier: 1.0, constant: 0.0)
        let buttonContainerCenterXConstraint = NSLayoutConstraint(item: buttonContainer, attribute: .centerX, relatedBy: .equal, toItem: buttonAreaView, attribute: .centerX, multiplier: 1.0, constant: 0.0)
        buttonAreaView.addConstraints([buttonAreaViewHeightConstraint, buttonContainerTopSpaceConstraint, buttonContainerCenterXConstraint])
        
        // ButtonContainer
        let buttonContainerWidthConstraint = NSLayoutConstraint(item: buttonContainer, attribute: .width, relatedBy: .equal, toItem: nil, attribute: .width, multiplier: 1.0, constant: innerContentWidth)
        buttonContainerHeightConstraint = NSLayoutConstraint(item: buttonContainer, attribute: .height, relatedBy: .equal, toItem: nil, attribute: .height, multiplier: 1.0, constant: 0.0)
        buttonContainer.addConstraints([buttonContainerWidthConstraint, buttonContainerHeightConstraint!])
        
        //------------------------------
