Solve app crash coming when opening epub files in FolioReader Epub iOS Swift library

Hello Expert Freelancers, We are working on a Book library project with Delaine technologies pvt ltd and we are using an Open Source FolioReader Epub Swift Library [login to view URL] Till last week it was running smoothly (i.e. open all epub files without crashing the app) but out of sudden last week it has started crashing on iOS 11, 11.1.1, 11.1.2 etc, whenever we open a book through FolioReader, and scroll horizontally or vertically and then whenever we open another book and do the same, the app crashes. How will we measure the success of this small project? We will give you 3-4 epub files which you have to run on iOS 11.1.2 simulator and the application should not crash while any of the given book is open and scrolled horizontally or vertically.