AutoLayout + Keyboard ResizeView

AutoLayout + Keyboard ResizeView.swift

import UIKit

class ViewController: UIViewController {

    @IBOutlet weak var bottomLayout: NSLayoutConstraint!
    let notificationCenter = NSNotificationCenter.defaultCenter()
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        notificationCenter.addObserver(self, selector:"willShowKeyboard:", name: UIKeyboardWillShowNotification, object: nil)
        notificationCenter.addObserver(self, selector:"willHideKeyboard:", name: UIKeyboardWillHideNotification, object: nil)
    }
    
    override func viewDidDisappear(animated: Bool) {
        notificationCenter.removeObserver(self, name: UIKeyboardWillShowNotification, object: nil)
        notificationCenter.removeObserver(self, name: UIKeyboardWillHideNotification, object: nil)
    }

    override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) {
        self.view.endEditing(true)
    }
    
    func willShowKeyboard(notification: NSNotification) {
        let duration = notification.duration()
        let keyboardRect = notification.rect()
        
        if let duration = duration, rect = keyboardRect {
            self.bottomLayout.constant = rect.size.height - self.bottomLayoutGuide.length;
            UIView.animateWithDuration(duration, animations: {
                self.view.layoutIfNeeded()
            })
        }
    }
    
    
    func willHideKeyboard(notification: NSNotification) {
        bottomLayout.constant = 0
        view.layoutIfNeeded()
    }
}


extension NSNotification {
    func duration() -> NSTimeInterval? {
        let duration: NSTimeInterval? = self.userInfo?[UIKeyboardAnimationDurationUserInfoKey] as? Double
        return duration;
    }
    
    func rect() -> CGRect? {
        let rowRect:NSValue? = self.userInfo?[UIKeyboardFrameEndUserInfoKey] as? NSValue
        let rect:CGRect? = rowRect?.CGRectValue()
        return rect
    }
}