Merge pull request #157 from rechsteiner/fix-reload-data

 Fix issues with reloading data

Parchment/Classes/EMPageViewController.swift

@@ -220,6 +220,10 @@ open class EMPageViewController: UIViewController, UIScrollViewDelegate {
         self.removeChildIfNeeded(beforeViewController)
         self.removeChildIfNeeded(selectedViewController)
         self.removeChildIfNeeded(afterViewController)
+
+        beforeViewController = nil
+        selectedViewController = nil
+        afterViewController = nil
     }
 
     /**

Parchment/Classes/PagingViewController.swift

@@ -325,9 +325,9 @@ open class PagingViewController<T: PagingItem>:
     indexedDataSource?.items = items
 
     if let pagingItem = items.first(where: { $0 == previouslySelected }) {
-      select(pagingItem: pagingItem, animated: false)
+      resetItems(around: pagingItem)
     } else if let firstItem = items.first {
-      select(pagingItem: firstItem, animated: false)
+      resetItems(around: firstItem)
     } else {
       stateMachine.fire(.removeAll)
     }
@@ -344,7 +344,7 @@ open class PagingViewController<T: PagingItem>:
   /// after the data reloads.
   open func reloadData(around pagingItem: T) {
     indexedDataSource?.items = generateItemsForIndexedDataSource()
-    select(pagingItem: pagingItem, animated: false)
+    resetItems(around: pagingItem)
   }
 
   /// Selects a given paging item. This need to be called after you
@@ -717,6 +717,26 @@ open class PagingViewController<T: PagingItem>:
     return items
   }
 
+  private func resetItems(around pagingItem: T) {
+    let toItems = generateItems(around: pagingItem)
+    let sortedItems = Array(toItems).sorted()
+
+    visibleItems = PagingItems(
+      items: sortedItems,
+      hasItemsBefore: hasItemBefore(pagingItem: sortedItems.first),
+      hasItemsAfter: hasItemAfter(pagingItem: sortedItems.last))
+    collectionViewLayout.visibleItems = visibleItems
+
+    stateMachine.fire(.select(pagingItem: pagingItem, direction: .none, animated: false))
+    collectionView.reloadData()
+    selectViewController(pagingItem, direction: .none, animated: false)
+
+    // Reloading the data triggers the didFinishScrollingFrom delegate
+    // to be called which in turn means the wrong item will be selected.
+    // For now, we just fix this by selecting the correct item manually.
+    stateMachine.fire(.select(pagingItem: pagingItem, direction: .none, animated: false))
+  }
+
   private func removeAll() {
     visibleItems = PagingItems(items: [])
     collectionViewLayout.visibleItems = visibleItems

ParchmentTests/PagingViewControllerSpec.swift

@@ -132,7 +132,7 @@ class PagingViewControllerSpec: QuickSpec {
           expect(viewController.state).to(equal(PagingState.selected(pagingItem: third)))
         }
 
-        fit("display an empty view after reloading data with no items") {
+        it("display an empty view after reloading data with no items") {
           dataSource.items = []
           viewController.reloadData()