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'; ios - How to Preload a page in UIpage view controller swift with local GIFs stored in project - LavOzs.Com

I'm trying to use GIF in my Image View using extension of UIImageView. I have 4 pages in a Page View Controller with 2 gifs each page. When i swipe right it shows some lag after 1 page. e.g. from the first page to the second page, it swiped smoothly while on from second to third it shows some lag while loading gifs. same coming back on second screen from third it moves smoothly but when i swipe again it shows a little lag. so basically it stores two pages in memory. the page you're coming from and the current page. if you swipe back to the page where from you coming it moves smoothly on the next move is another direction which is not loaded before it shows lag.

1) I have tried to load content in viewDidAppear(). but that was not good enough for my problem. by doing this movement becomes smooth but content loads after delay.

2) I tried to initiate all view controllers in UIPageViewController() view did load. but it did not work out.

func pageViewController(_ pageViewController: UIPageViewController, viewControllerAfter viewController: UIViewController) -> UIViewController? {
    var index = (viewController as! OnBoardingController).index
    index += 1
    return contentViewController(at : index)

func contentViewController(at index : Int) -> OnBoardingController? {
    if index < 0  || index >= headings.count {
        return nil
    else {

        let board = UIStoryboard(name: "OnBoardingStoryBoard", bundle: nil)
        if let controller = board.instantiateViewController(withIdentifier: "OnBoardingController") as? OnBoardingController {
            controller.heading = self.headings[index]
            controller.details = self.subHeadings[index]
            controller.imageName = self.imageNames[index]
            controller.imageNameSecond = self.imagesnamesecond[index]
            controller.index = index
            return controller
    return nil

I want to increase the limit of preloaded pages in PageViewController. or if i could load pages in a separate section.

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