Converts AppDefaults to singleton

Multiplatform/macOS/Preferences/View/GeneralPreferencesView.swift

@@ -0,0 +1,33 @@
+//
+//  GeneralPreferencesView.swift
+//  macOS
+//
+//  Created by Stuart Breckenridge on 27/6/20.
+//
+
+import SwiftUI
+
+struct GeneralPreferencesView: View {
+    
+	@EnvironmentObject private var defaults: AppDefaults
+    
+    var body: some View {
+        VStack {
+            Form {
+                Picker("Refresh Feeds",
+					   selection: $defaults.interval,
+                       content: {
+						ForEach(RefreshInterval.allCases, content: { interval in
+							Text(interval.description()).tag(interval.rawValue)
+                    })
+					   }).frame(width: 300, alignment: .center)
+				
+                Toggle("Open webpages in background in browser", isOn: $defaults.openInBrowserInBackground)
+                
+                Toggle("Hide Unread Count in Dock", isOn: $defaults.hideDockUnreadCount)
+            }
+            Spacer()
+		}.frame(width: 300, alignment: .center)
+    }
+    
+}