Tweak "reanimate" logic

Author: bdewey

CHANGELOG.md

@@ -1,5 +1,11 @@
 # Changelog
 
+## [0.3.0] - 2019-08-07
+
+### Changed
+
+- Faster typing propagation between master & detail view
+
 ## [0.2.0] - 2019-08-03
 
 ### Changed

CommonplaceBookApp/DocumentDiffableDataSource.swift

@@ -95,14 +95,21 @@ public final class DocumentDiffableDataSource: UITableViewDiffableDataSource<Doc
       cardsPerDocument: cardsPerDocument,
       hashtag: filteredHashtag
     )
-    // Only animate inserts & deletes.
-    // In particular I don't want to animate reloads as I type -- it's too noisy
-    // I'm said I'm losing reordering animations :-(
-    // Is there some way, when observing the notebook, to know that it was a typing change?
-    let reallyAnimate = animated && self.snapshot().numberOfItems != snapshot.numberOfItems
+    let reallyAnimate = animated && DocumentDiffableDataSource.majorSnapshotDifferences(between: self.snapshot(), and: snapshot)
     apply(snapshot, animatingDifferences: reallyAnimate)
   }
 
+  /// Compares lhs & rhs to see if the differences are worth animating.
+  private static func majorSnapshotDifferences(between lhs: Snapshot, and rhs: Snapshot) -> Bool {
+    if lhs.numberOfItems != rhs.numberOfItems {
+      return true
+    }
+    for (lhsItem, rhsItem) in zip(lhs.itemIdentifiers, rhs.itemIdentifiers) {
+      if lhsItem.pageKey != rhsItem.pageKey { return true }
+    }
+    return false
+  }
+
   private static func snapshot(
     for notebook: NoteArchiveDocument,
     cardsPerDocument: [String: Int],