Useful Rx tool to works with the Keyboard states in iOS

RxKeyboard

//
//  RxKeyboard.swift
//  RxTools
//
//  Created by Roberto Frontado on 5/16/16.
//  Copyright © 2016 Roberto Frontado. All rights reserved.
//

import RxSwift

public class RxKeyboard: NSObject {
    
    private var subscribe: AnyObserver<(state: State, duration: Double, keyboardRectangle: CGRect)>!
    
    public enum State {
        case WillShow
        case DidHide
        case DidChange
    }
    
    public override init() {
        super.init()
        NSNotificationCenter.defaultCenter().addObserver(self, selector: "keyboardWillShow:", name: UIKeyboardWillShowNotification, object: nil)
        NSNotificationCenter.defaultCenter().addObserver(self, selector: "keyboardDidHide:", name: UIKeyboardDidHideNotification, object: nil)
        NSNotificationCenter.defaultCenter().addObserver(self, selector: "keyboardDidChange:", name: UIKeyboardDidChangeFrameNotification, object: nil)
    }
    
    public func getCurrentState() -> Observable<(state: State, duration: Double, keyboardRectangle: CGRect)> {
        return Observable.create { subscribe -> Disposable in
            self.subscribe = subscribe
            return NopDisposable.instance
        }
    }
    
    public func dispose() {
        NSNotificationCenter.defaultCenter().removeObserver(self)
    }
    
    // MARK: - Keyboard
    public func keyboardWillShow(notification: NSNotification) {
        subscribe.onNext((state: .WillShow, duration: getDuration(notification), keyboardRectangle: getKeyboardRectangle(notification)))
    }
    
    public func keyboardDidChange(notification: NSNotification) {
        subscribe.onNext((state: .DidChange, duration: getDuration(notification), keyboardRectangle: getKeyboardRectangle(notification)))
    }
    
    public func keyboardDidHide(notification: NSNotification) {
        subscribe.onNext((state: .DidHide, duration: getDuration(notification), keyboardRectangle: getKeyboardRectangle(notification)))
    }
    
    // MARK: - Private methods
    private func getKeyboardRectangle(notification: NSNotification) -> CGRect {
        let userInfo: NSDictionary = notification.userInfo!
        let keyboardFrame = userInfo.valueForKey(UIKeyboardFrameEndUserInfoKey) as! NSValue
        return keyboardFrame.CGRectValue()
    }
    private func getDuration(notification: NSNotification) -> Double {
        let userInfo: NSDictionary = notification.userInfo!
        return (userInfo.valueForKey(UIKeyboardAnimationDurationUserInfoKey) as? NSNumber)?.doubleValue ?? 0
    }

}