UIScrollView + UIPageControl with RxSwift

UIScrollView+UIPageControl.swift

import RxSwift
import RxCocoa

fileprivate extension Reactive where Base: UIScrollView {
    fileprivate var currentPage: Observable<Int> {
        return didEndDecelerating.map({
            let pageWidth = self.base.frame.width
            let page = floor((self.base.contentOffset.x - pageWidth / 2) / pageWidth) + 1
            return Int(page)
        })
    }
}

fileprivate extension UIScrollView {
    fileprivate func setCurrentPage(_ page: Int, animated: Bool) {
        var rect = bounds
        rect.origin.x = rect.width * CGFloat(page)
        rect.origin.y = 0
        scrollRectToVisible(rect, animated: animated)
    }
}

class ViewController: UIViewController {
    private let disposeBag = DisposeBag()
    @IBOutlet weak var scrollView: UIScrollView!
    @IBOutlet weak var pageControl: UIPageControl!

    override func viewDidLoad() {
        super.viewDidLoad()

        pageControl.rx.controlEvent(.valueChanged)
            .subscribe(onNext: { [weak self] in
                guard let currentPage = self?.pageControl.currentPage else {
                    return
                }
                self?.scrollView.setCurrentPage(currentPage, animated: true)
            })
            .disposed(by: disposeBag)

        scrollView.rx.currentPage
            .subscribe(onNext: { [weak self] in
                self?.pageControl.currentPage = $0
            })
            .disposed(by: disposeBag)

        scrollView.isPagingEnabled = true
        scrollView.contentSize = CGSize(width: scrollView.bounds.width * 4, height: scrollView.bounds.height)
    }
}

can also be bound as:

scrollView.rx.currentPage
  .bind(to: pageControl.rx.currentPage)
  .disposed(by: disposeBag)