Display empty notification cell (#1884)

Author: rnystrom

Diff for: Classes/Notifications/NoNewNotificationsSectionController.swift

@@ -10,9 +10,8 @@ import UIKit
 import IGListKit
 import Crashlytics
 
-final class NoNewNotificationSectionController: ListSectionController {
+final class NoNewNotificationSectionController: ListSwiftSectionController<String> {
 
-    private let topInset: CGFloat
     private let layoutInsets: UIEdgeInsets
     private let client = NotificationEmptyMessageClient()
 
@@ -23,26 +22,31 @@ final class NoNewNotificationSectionController: ListSectionController {
     }
     private var state: State = .loading
 
-    init(topInset: CGFloat, layoutInsets: UIEdgeInsets) {
-        self.topInset = topInset
+    init(layoutInsets: UIEdgeInsets) {
         self.layoutInsets = layoutInsets
         super.init()
         client.fetch { [weak self] (result) in
             self?.handleFinished(result)
         }
     }
 
-    override func sizeForItem(at index: Int) -> CGSize {
-        guard let size = collectionContext?.containerSize
-            else { fatalError("Missing context") }
-        return CGSize(width: size.width, height: size.height - topInset - layoutInsets.top - layoutInsets.bottom)
-    }
-
-    override func cellForItem(at index: Int) -> UICollectionViewCell {
-        guard let cell = collectionContext?.dequeueReusableCell(of: NoNewNotificationsCell.self, for: self, at: index) as? NoNewNotificationsCell
-            else { fatalError("Missing context or cell is wrong type") }
-        configure(cell)
-        return cell
+    override func createBinders(from value: String) -> [ListBinder] {
+        return [
+            binder(
+                value,
+                cellType: ListCellType.class(NoNewNotificationsCell.self),
+                size: { [layoutInsets] in
+                    return CGSize(
+                        width: $0.collection.containerSize.width,
+                        height: $0.collection.containerSize.height - layoutInsets.top - layoutInsets.bottom
+                    )
+            },
+                configure: { [weak self] in
+                    // TODO accessing the value seems to be required for this to compile
+                    print($1.value)
+                    self?.configure($0)
+                })
+        ]
     }
 
     // MARK: Private API

Diff for: Classes/Notifications/NotificationsViewController.swift

@@ -12,7 +12,9 @@ import FlatCache
 
 final class NotificationsViewController: BaseListViewController2<Int>,
 BaseListViewController2DataSource,
-ForegroundHandlerDelegate, FlatCacheListener {
+ForegroundHandlerDelegate,
+FlatCacheListener,
+BaseListViewController2EmptyDataSource {
 
     private let modelController: NotificationModelController
     private let foreground = ForegroundHandler(threshold: 5 * 60)
@@ -30,6 +32,7 @@ ForegroundHandlerDelegate, FlatCacheListener {
         super.init(emptyErrorMessage: NSLocalizedString("Cannot load your inbox.", comment: ""))
 
         self.dataSource = self
+        self.emptyDataSource = self
         self.foreground.delegate = self
 
         switch inboxType {
@@ -268,6 +271,15 @@ ForegroundHandlerDelegate, FlatCacheListener {
         }
     }
 
+    // MARK: BaseListViewController2EmptyDataSource
+
+    func emptyModel(for adapter: ListSwiftAdapter) -> ListSwiftPair {
+        let layoutInsets = view.safeAreaInsets
+        return ListSwiftPair.pair("empty-notification-value", {
+            return NoNewNotificationSectionController(layoutInsets: layoutInsets)
+        })
+    }
+
     // MARK: ForegroundHandlerDelegate
 
     func didForeground(handler: ForegroundHandler) {

Diff for: Classes/View Controllers/BaseListViewController2.swift

@@ -13,18 +13,23 @@ protocol BaseListViewController2DataSource: class {
     func models(adapter: ListSwiftAdapter) -> [ListSwiftPair]
 }
 
+protocol BaseListViewController2EmptyDataSource: class {
+    func emptyModel(for adapter: ListSwiftAdapter) -> ListSwiftPair
+}
+
 class BaseListViewController2<PageType: CustomStringConvertible>: UIViewController,
 ListSwiftAdapterDataSource,
 FeedDelegate,
 LoadMoreSectionController2Delegate {
 
     private let emptyErrorMessage: String
+
     public weak var dataSource: BaseListViewController2DataSource?
+    public weak var emptyDataSource: BaseListViewController2EmptyDataSource?
 
     public private(set) lazy var feed: Feed = { Feed(viewController: self, delegate: self) }()
     private var page: PageType?
     private var hasError = false
-    private let emptyKey: ListDiffable = "emptyKey" as ListDiffable
 
     init(emptyErrorMessage: String) {
         self.emptyErrorMessage = emptyErrorMessage
@@ -118,6 +123,12 @@ LoadMoreSectionController2Delegate {
             return []
         }
 
+        if let emptyDataSource = self.emptyDataSource,
+            hasNoObjects,
+            feed.status == .idle {
+            return [emptyDataSource.emptyModel(for: adapter)]
+        }
+
         if let page = self.page?.description {
             let pagePair = ListSwiftPair.pair(page) { [weak self] in
                 let controller = LoadMoreSectionController2()