RxSwift wrapper for keyboard height.

KeyboardHeight.swift

//
//  KeyboardHeight.swift
//  bodytonic-ios
//
//  Created by Desmond McNamee on 2016-08-28.
//  Copyright © 2016 Stadium Studio. All rights reserved.
//

import UIKit
import RxSwift

class KeyboardHeight {
    let currentKeyboardHeight = Variable(Float(0.0))
    
    static let sharedInstance = KeyboardHeight()
    
    private init() {
        NSNotificationCenter.defaultCenter().addObserver(
            self,
            selector: #selector(KeyboardHeight.keyboardWillShow),
            name: UIKeyboardWillShowNotification,
            object: nil)
        
        NSNotificationCenter.defaultCenter().addObserver(
            self,
            selector: #selector(KeyboardHeight.keyboardWillHide),
            name: UIKeyboardWillHideNotification,
            object: nil)
    }
    
    @objc func keyboardWillShow(notification: NSNotification) {
        guard
            let info = notification.userInfo,
            let size = info[UIKeyboardFrameEndUserInfoKey] else { return }
        
        let newHeight = size.CGRectValue().size.height
        self.currentKeyboardHeight.value = Float(newHeight)
    }
    
    @objc func keyboardWillHide(notification: NSNotification) {
        self.currentKeyboardHeight.value = 0.0
    }
}