RxSwift UIButton binding for setImage:controlState:

UIButton+Rx.swift

import UIKit
import RxSwift
import RxCocoa

extension UIButton {
    public func rx_image(controlState: UIControlState?) -> ObserverOf<UIImage!> {
        return ObserverOf { [weak self] event in
            MainScheduler.ensureExecutingOnScheduler()
            
            switch event {
            case .Next(let value):
                if let controlState = controlState {
                    self?.setImage( value, forState:controlState)
                }
                else {
                    self?.setImage( value, forState:.Normal)
                }
            case .Error(let error):
                let error = "Binding error to UI: \(error)"
                print(error)
            case .Completed:
                break
            }
        }
    }

    
}