Medium_Filter_Function.swift

// MARK: FILTER FUNCTION
func filterBooks(books: [Book], by filters: SearchingBook) -> [Book]{
    
    var bookFiltered = books.filter({ filters.byBeforeYear == 0 || $0.year < filters.byBeforeYear})
    
    //Search by favorite
    switch filters.byFavorite {
    case .favorite:
        bookFiltered.removeAll(where: {!$0.favorite})
    case .notFavorite:
        bookFiltered.removeAll(where: {$0.favorite})
    default:
        break
    }
   
    if !filters.byAuthorFirstName.isEmpty {
        bookFiltered.removeAll(where: {$0.author.firstName.range(of: filters.byAuthorFirstName,options: .caseInsensitive) == nil})
    }
    
    return bookFiltered
}