feat: ios mobil arayüz tasarımı

ios/Bookibra/ViewModels/CategoryViewModel.swift

@@ -0,0 +1,39 @@
+import Foundation
+
+@MainActor
+final class CategoryViewModel: ObservableObject {
+    enum SortOption: String, CaseIterable {
+        case recentlyAdded = "Recently Added"
+        case titleAZ = "Title A-Z"
+        case author = "Author"
+    }
+
+    let categoryName: String
+    @Published var searchText = ""
+    @Published var sortOption: SortOption = .recentlyAdded
+
+    init(categoryName: String) {
+        self.categoryName = categoryName
+    }
+
+    func books(from allBooks: [LibraryBook]) -> [LibraryBook] {
+        var filtered = allBooks.filter { $0.categories.contains(categoryName) || (categoryName == "Design" && $0.categories.isEmpty) }
+
+        if !searchText.isEmpty {
+            filtered = filtered.filter {
+                $0.title.localizedCaseInsensitiveContains(searchText)
+                || $0.authorsString.localizedCaseInsensitiveContains(searchText)
+            }
+        }
+
+        switch sortOption {
+        case .recentlyAdded:
+            filtered.sort { $0.dateAdded > $1.dateAdded }
+        case .titleAZ:
+            filtered.sort { $0.title.localizedCaseInsensitiveCompare($1.title) == .orderedAscending }
+        case .author:
+            filtered.sort { $0.authorsString.localizedCaseInsensitiveCompare($1.authorsString) == .orderedAscending }
+        }
+        return filtered
+    }
+}