UIScrollVIew & keyboard

BaseViewController.swift

import UIKit

// To make it work, add this to your child viewController:
// override func viewDidLoad() {
//    super.viewDidLoad()
//    baseScrollView = scrollView
//    myTextView.delegate = self // Set delegate = self for each UITextView
// }

extension UIEdgeInsets {
    func clone() -> UIEdgeInsets {
        return UIEdgeInsets(top: self.top, left: self.left, bottom: self.bottom, right: self.right)
    }
}    
    
class BaseViewController: UIViewController, UITextViewDelegate {
    var baseScrollView: UIScrollView!
    var savedContentInsets: UIEdgeInsets!
    var activeTextView: UITextView!

    override func viewDidLoad() {
        super.viewDidLoad()
        NSNotificationCenter.defaultCenter().addObserver(self, selector: "keyboardWillShow:", name: UIKeyboardWillShowNotification, object: nil)
        NSNotificationCenter.defaultCenter().addObserver(self, selector: "keyboardDidShow:", name: UIKeyboardDidShowNotification, object: nil)
        NSNotificationCenter.defaultCenter().addObserver(self, selector: "keyboardWillHide:", name: UIKeyboardWillHideNotification, object: nil)
    }

    func keyboardWillShow(notification: NSNotification) {
        if let keyboardSize = (notification.userInfo?[UIKeyboardFrameEndUserInfoKey] as? NSValue)?.CGRectValue() {
            onKeyboardWillShow(keyboardSize.height)
        }
    }

    func keyboardDidShow(notification: NSNotification) {
        if let keyboardSize = (notification.userInfo?[UIKeyboardFrameEndUserInfoKey] as? NSValue)?.CGRectValue() {
            onKeyboardDidShow(keyboardSize.height)
        }
    }

    func keyboardWillHide(notification: NSNotification) {
        if let keyboardSize = (notification.userInfo?[UIKeyboardFrameEndUserInfoKey] as? NSValue)?.CGRectValue() {
            onKeyboardWillHide(keyboardSize.height)
        }
    }

    func onKeyboardWillShow(height: CGFloat) {
        if baseScrollView != nil {
            if (savedContentInsets == nil) {
                savedContentInsets = baseScrollView.contentInset.clone()
            }

            var newContentInsets = baseScrollView.contentInset.clone()
            newContentInsets.bottom = height
            baseScrollView.contentInset = newContentInsets
            baseScrollView.scrollIndicatorInsets = newContentInsets
        }
    }

    func onKeyboardDidShow(height: CGFloat) {
        // ensure UITextView appears as it is not handled automagically by IOS SDK
        if activeTextView != nil {
            ensureTextViewAppears()
        }
    }

    func onKeyboardWillHide(height: CGFloat) {
        if baseScrollView != nil {
            if savedContentInsets != nil {
                baseScrollView.contentInset = savedContentInsets
                baseScrollView.scrollIndicatorInsets = savedContentInsets
                savedContentInsets = nil
            }
        }
    }

    func ensureTextViewAppears(){
        let originalContentOffsetY = -savedContentInsets.top
        let fieldNewTopMargin = CGFloat(25)
        let yChangeForField = activeTextView.frame.origin.y - fieldNewTopMargin

        baseScrollView.setContentOffset(
            CGPoint(
                x: baseScrollView.contentOffset.x,
                y: originalContentOffsetY + yChangeForField
            ),
            animated: true
        )
    }

    func textViewDidBeginEditing(textView: UITextView) {
        activeTextView = textView
    }

    func textViewDidEndEditing(textView: UITextView) {
        activeTextView = nil
    }

}