Scroll keyboard up just enough to show control. Swift 3.

gistfile1.txt

 // note that currentFirstResponder is obtained by this:
 // 
 // static var currentFirstResponder: UIResponder?
 // func findFirstResponder(sender: Any) {
 //   currentFirstResponder = self
 // }
 //
 // class func currentFirstResponder() -> UIResponder? {
 //   currentFirstResponder = nil
 //   UIApplication.shared.sendAction(#selector(findFirstResponder), to: nil, from: nil, for: nil)
 //   return currentFirstResponder
 // }
 
 
    func keyboardWillShow(notification: Notification) {
        if var keyboardRect = (notification.userInfo?[UIKeyboardFrameEndUserInfoKey] as? NSValue)?.cgRectValue {
            keyboardRect = self.view.convert(keyboardRect, from: nil)
            let keyboardCurve = (notification.userInfo?[UIKeyboardAnimationCurveUserInfoKey] as? NSNumber)?.intValue
            let keyboardDuration = (notification.userInfo?[UIKeyboardAnimationDurationUserInfoKey] as? NSNumber)?.doubleValue
            
            if let responder = UIResponder.currentFirstResponder() as? UIView {
                let scrollViewKeyboardIntersection = self.tableView.frame.intersection(keyboardRect)
                let newContentInsets = UIEdgeInsetsMake(0, 0, scrollViewKeyboardIntersection.size.height, 0)
                
                UIView.beginAnimations(nil, context: nil)
                UIView.setAnimationDuration(keyboardDuration!)
                UIView.setAnimationCurve(UIViewAnimationCurve.init(rawValue: keyboardCurve!)!)
                self.tableView.contentInset = newContentInsets
                self.tableView.scrollIndicatorInsets = newContentInsets
                
                var controlFrameInScrollView = self.tableView.convert(responder.bounds, from: responder)
                controlFrameInScrollView = controlFrameInScrollView.insetBy(dx: 0, dy: -10.0)
                let controlVisualOffsetToTopOfScrollview = controlFrameInScrollView.origin.y - self.tableView.contentOffset.y
                let controlVisualBottom = controlVisualOffsetToTopOfScrollview + controlFrameInScrollView.size.height
                // visible part of scrollview not hidden by keyboard:
                let scrollViewVisibleHeight = self.tableView.frame.size.height - scrollViewKeyboardIntersection.size.height
                
                if controlVisualBottom > scrollViewVisibleHeight { // keyboard will heide control in question
                    var newContentOffset = self.tableView.contentOffset
                    newContentOffset.y += controlVisualBottom - scrollViewVisibleHeight
                    newContentOffset.y = min(newContentOffset.y, self.tableView.contentSize.height - scrollViewVisibleHeight)
                    self.tableView.setContentOffset(newContentOffset, animated: false)
                } else if controlFrameInScrollView.origin.y < self.tableView.contentOffset.y {
                    // control not fully visible
                    var newContentOffset = self.tableView.contentOffset
                    newContentOffset.y = controlFrameInScrollView.origin.y
                    self.tableView.setContentOffset(newContentOffset, animated: false)
                }
                
                UIView.commitAnimations()
            }
        }
    }
    
    func keyboardWillHide(notification: Notification) {
        self.tableView.contentInset = UIEdgeInsets.zero
        self.tableView.scrollIndicatorInsets = UIEdgeInsets.zero
    }