问UIpageViewController与定时器

EN

import UIKit

class PageViewController: UIPageViewController , UIPageViewControllerDataSource{

    var scrollingTimer = Timer()
    let imageNames = ["Apple_Watch_Main" , "Pic2" , "Pic3"]

    override func viewDidLoad() {
        super.viewDidLoad()

        dataSource = self
        let frameViewController = FrameViewController()
        frameViewController.imageName = imageNames.first

        let viewControllers = [frameViewController]
        setViewControllers(viewControllers, direction: .forward, animated: true, completion: nil)

    }

    func pageViewController(_ pageViewController: UIPageViewController, viewControllerBefore viewController: UIViewController) -> UIViewController? {

        let currentImageName = (viewController as! FrameViewController).imageName
        let currentIndex = imageNames.index(of: currentImageName!)
        if currentIndex! > 0 {
            let frameViewController = FrameViewController()
            frameViewController.imageName = imageNames[currentIndex! - 1]
            return frameViewController
        }
        return nil
    }

    func pageViewController(_ pageViewController: UIPageViewController, viewControllerAfter viewController: UIViewController) -> UIViewController? {

        let currentImageName = (viewController as! FrameViewController).imageName
        let currentIndex = imageNames.index(of: currentImageName!)
        if currentIndex! < imageNames.count - 1 {
            let frameViewController = FrameViewController()
            frameViewController.imageName = imageNames[currentIndex! + 1]
            return frameViewController
        }
        return nil
    }
}

override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {

        switch indexPath.item {
        case 0 :
            let cell = collectionView.dequeueReusableCell(withReuseIdentifier: cellId, for: indexPath) as!ImageCell

            let pagecontroller = PageViewController(transitionStyle: .scroll, navigationOrientation: .horizontal, options: nil)
            self.addChildViewController(pagecontroller)

            cell.addSubview(pagecontroller.view)

            pagecontroller.view.frame = CGRect(x: 0, y: 0, width: view.frame.width, height: view.frame.height/3)
            return cell
        case 1 :
            let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "filterandorganize", for: indexPath) as! FilterAndOrganize
            return cell
        case 2 :
            let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "Offers", for: indexPath) as! Offers
            return cell
        case 3 :
            let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "OfferedProducts", for: indexPath) as! OfferedProducts
            cell.firstViewController = self
            return cell
        default:
            let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "Offers", for: indexPath) as! Offers
            return cell
        }
    }

class PageViewController: UIPageViewController , UIPageViewControllerDataSource{
    var index = 0
    let imageNames = ["Apple_Watch_Main" , "Pic2" , "Pic3"]

    override func viewDidLoad() {
        super.viewDidLoad()
        dataSource = self

        let frameViewController = FrameViewController()
        frameViewController.imageName = imageNames[index]
        index += 1
        let viewControllers = [frameViewController]
        setViewControllers(viewControllers, direction: .forward, animated: true, completion: nil)

        Timer.scheduledTimer(timeInterval: 6.0 ,
                             target: self,
                             selector: #selector(myFunc(_:)),
                             userInfo: index,
                             repeats: true)
    }
    //FIXME: needs some fixes
    func myFunc(_ timer: Timer) {
        if index == imageNames.count  {
            index = 0
        }
        else {
            self.changePIC(index)
            index += 1
        }
    }
    func changePIC(_ i: Int) {
        let frameViewController = FrameViewController()
        frameViewController.imageName = imageNames[i]
        let viewControllers = [frameViewController]
        setViewControllers(viewControllers, direction: .forward, animated: true, completion: nil)
    }