All basic views now done.

Some tidying of views will be needed.
Next, data fetching needs to be worked on.

Signed-off-by: Louis Hollingworth <louis@hollingworth.ch>

Leganto/DataController.swift

@@ -5,17 +5,74 @@
 //  Created by Louis Hollingworth on 2023-05-21.
 //
 
-import Foundation
 import CoreData
 
 class DataController: ObservableObject {
-    let container = NSPersistentContainer(name: "Leganto")
+    static let shared = DataController()
     
-    init() {
-        container.loadPersistentStores { desc, err in
-            if let err = err {
-                print("Core Data failed to load: \(err.localizedDescription)")
+    static var preview: DataController {
+        let result = DataController(inMemory: true)
+        let viewContext = result.container.viewContext
+        
+        for i in 0..<3 {
+            for j in 1...3 {
+                let newFeed = Feed(context: viewContext)
+                switch i {
+                case 2:
+                    newFeed.genre = Genre.technology.rawValue
+                    break
+                case 3:
+                    newFeed.genre = Genre.news.rawValue
+                    break
+                default:
+                    newFeed.genre = Genre.uncategorised.rawValue
+                    break
+                }
+            
+                newFeed.name = "\(i+j)"
+                newFeed.dateAdded = Date()
+                newFeed.dateUpdated = Date()
+                newFeed.desc = "\(i+j)"
+                newFeed.url = "https://git.ludoviko.ch/lucxjo/leganto.rss"
             }
         }
+        
+        do {
+            try viewContext.save()
+        } catch {
+            let nsError = error as NSError
+            fatalError("Unresolved error \(nsError), \(nsError.userInfo)")
+
+        }
+        
+        return result
+    }
+    
+    let container: NSPersistentCloudKitContainer
+    
+    init(inMemory: Bool = false) {
+        container = NSPersistentCloudKitContainer(name: "Leganto")
+        if inMemory {
+            container.persistentStoreDescriptions.first!.url = URL(fileURLWithPath: "/dev/null")
+        }
+
+        container.loadPersistentStores(completionHandler: { (storeDescription, error) in
+            if let error = error as NSError? {
+                // Replace this implementation with code to handle the error appropriately.
+                // fatalError() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
+
+                /*
+                    Typical reasons for an error here include:
+                    * The parent directory does not exist, cannot be created, or disallows writing.
+                    * The persistent store is not accessible, due to permissions or data protection when the device is locked.
+                    * The device is out of space.
+                    * The store could not be migrated to the current model version.
+                    Check the error message to determine what the actual problem was.
+                */
+                fatalError("Unresolved error \(error), \(error.userInfo)")
+            }
+        })
+        
+        container.viewContext.automaticallyMergesChangesFromParent = true
     }
 }