Grid of photos like in native photos app with smooth scrolling, zooming by pinch. Showing thousands of thumbnails at minimum zoom

Hello. Looks like there is kind of block for using UIImagepickercontroller for full screen views and there is only popup option available. Why?! We can use photos from library, try to create custom grid.. but there is a lot if already solved issues with memory usage and so on.. Now I used to wrote my custom scrolling and zooming by pinch tool like native photo grid but it works on UIImageView and only with not very big amount of UIImageViews (creating more than several thousand on old iPhones like 6s start being problematic..). After I decided to try to create more specific tool. I'v created UIImage and set it as cgImage for View content. And updating this image and View content after it. But it takes really long time to print thousands of images even with PHCachingImageManager it looks like imageCachingManager.requestImage takes too much time even with ready to use thumbnails or there is an error in startCachingImages tool or it's bad idea to print images one by one in background and lots of other questions and problems.. why? Really..? It's complete tool and you just blocked it... Or there is somewhere complete ready to use example how to implement grid of photos like in native app to main view without popups and so on?

https://developer.apple.com/documentation/uikit/uiimagepickercontroller