internal diff for PR #209

Summary: https://github.com/Instagram/IGListKit/pull/209

Reviewed By: rnystrom

Differential Revision: D4190633

fbshipit-source-id: 9d382b9ba3f3d20c8b9c48d900650ec354bc9728

Examples/Examples-iOS/IGListKitExamples/ViewControllers/EmptyViewController.swift

@@ -0,0 +1,91 @@
+/**
+ Copyright (c) 2016-present, Facebook, Inc. All rights reserved.
+
+ The examples provided by Facebook are for non-commercial testing and evaluation
+ purposes only. Facebook reserves all rights not expressly granted.
+
+ THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ FACEBOOK BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+import UIKit
+import IGListKit
+
+final class EmptyViewController: UIViewController, IGListAdapterDataSource, RemoveSectionControllerDelegate {
+
+    lazy var adapter: IGListAdapter = {
+        return IGListAdapter(updater: IGListAdapterUpdater(), viewController: self, workingRangeSize: 0)
+    }()
+    let collectionView = IGListCollectionView(frame: .zero, collectionViewLayout: UICollectionViewFlowLayout())
+
+    let emptyLabel: UILabel = {
+        let label = UILabel()
+        label.numberOfLines = 0
+        label.textAlignment = .center
+        label.text = "No more data!"
+        label.backgroundColor = .clear
+        return label
+    }()
+
+    var tally = 4
+    var data = [
+        1,
+        2,
+        3,
+        4
+    ]
+
+    override func viewDidLoad() {
+        super.viewDidLoad()
+
+        navigationItem.rightBarButtonItem = UIBarButtonItem(barButtonSystemItem: .add,
+                                                            target: self,
+                                                            action: #selector(EmptyViewController.onAdd))
+
+        collectionView.backgroundColor = UIColor(white: 0.9, alpha: 1)
+        view.addSubview(collectionView)
+        adapter.collectionView = collectionView
+        adapter.dataSource = self
+    }
+
+    override func viewDidLayoutSubviews() {
+        super.viewDidLayoutSubviews()
+        collectionView.frame = view.bounds
+    }
+
+    func onAdd() {
+        data.append(tally + 1)
+        tally += 1
+        adapter.performUpdates(animated: true, completion: nil)
+    }
+
+    //MARK: IGListAdapterDataSource
+
+    func objects(for listAdapter: IGListAdapter) -> [IGListDiffable] {
+        return data as [IGListDiffable]
+    }
+
+    func listAdapter(_ listAdapter: IGListAdapter, sectionControllerFor object: Any) -> IGListSectionController {
+        let sectionController = RemoveSectionController()
+        sectionController.delegate = self
+        return sectionController
+    }
+
+    func emptyView(for listAdapter: IGListAdapter) -> UIView? {
+        return emptyLabel
+    }
+
+    //MARK: RemoveSectionControllerDelegate
+
+    func removeSectionControllerWantsRemoved(_ sectionController: RemoveSectionController) {
+        let section = adapter.section(for: sectionController)
+        guard let object = adapter.object(atSection: section) as? Int, let index = data.index(of: object) else { return }
+        data.remove(at: index)
+        adapter.performUpdates(animated: true, completion: nil)
+    }
+
+}