implement delegate methods, add doc comments

Author: morganchen12

FirebaseDatabaseUI/FirebaseIndexArray.h

@@ -115,10 +115,22 @@ didFailLoadWithError:(NSError *)error;
 
 @interface FirebaseIndexArray : NSObject
 
+/**
+ * An immutable copy of the loaded contents in the array. Returns an
+ * empty array if no contents have loaded yet.
+ */
 @property(nonatomic, copy, readonly) NSArray<FIRDataSnapshot *> *items;
 
+/**
+ * The delegate that this array should forward events to.
+ */
 @property(nonatomic, weak) id<FirebaseIndexArrayDelegate> delegate;
 
+/**
+ * Returns the number of items in the array.
+ */
+@property(nonatomic, readonly) NSUInteger count;
+
 - (instancetype)init NS_UNAVAILABLE;
 
 /**
@@ -149,6 +161,7 @@ didFailLoadWithError:(NSError *)error;
 
 /**
  * Returns the snapshot at the given index, if it has loaded.
+ * Raises a fatal error if the index is out of bounds.
  * @param index The index of the requested snapshot.
  * @return A snapshot, or nil if one has not yet been loaded.
  */

FirebaseDatabaseUI/FirebaseIndexArray.m

@@ -71,11 +71,17 @@ - (void)observeQueries {
   NSArray *observers = [self.observers copy];
   NSMutableArray *array = [[NSMutableArray alloc] initWithCapacity:observers.count];
   for (FirebaseQueryObserver *observer in observers) {
-    [array addObject:observer.contents];
+    if (observer.contents != nil) {
+      [array addObject:observer.contents];
+    }
   }
   return [array copy];
 }
 
+- (NSUInteger)count {
+  return self.observers.count;
+}
+
 // FirebaseIndexArray instance becomes unusable after invalidation.
 - (void)invalidate {
   for (NSInteger i = 0; i < self.observers.count; i++) {

FirebaseDatabaseUI/FirebaseIndexCollectionViewDataSource.h

@@ -20,10 +20,24 @@
 
 NS_ASSUME_NONNULL_BEGIN
 
-@interface FirebaseIndexCollectionViewDataSource : NSObject
+@interface FirebaseIndexCollectionViewDataSource : NSObject <UICollectionViewDataSource>
 
 - (instancetype)init NS_UNAVAILABLE;
 
+/**
+ * Initializes a collection view data source.
+ * @param indexQuery The Firebase query containing children of the data query.
+ * @param dataQuery The reference whose children correspond to the contents of the
+ *   index query. This reference's children's contents are served as teh contents
+ *   of the collection view that adopts this data source.
+ * @param collectionView The collection view that is populated by this data source. The
+ *   data source pulls updates from Firebase database, so it must maintain a reference
+ *   to the collection view in order to update its contents as the database pushes updates.
+ *   The table view is not retained by its data source.
+ * @param cellIdentifier The cell reuse identifier used to dequeue reusable cells from
+ *   the collection view.
+ * @param populateCell The closure invoked when populating a UICollectionViewCell (or subclass).
+ */
 - (instancetype)initWithIndex:(FIRDatabaseQuery *)indexQuery
                          data:(FIRDatabaseReference *)dataQuery
                collectionView:(UICollectionView *)collectionView
@@ -33,7 +47,4 @@ NS_ASSUME_NONNULL_BEGIN
 
 @end
 
-@interface FirebaseIndexCollectionViewDataSource (CollectionViewDataSource) <UICollectionViewDataSource>
-@end
-
 NS_ASSUME_NONNULL_END

FirebaseDatabaseUI/FirebaseIndexCollectionViewDataSource.m

@@ -93,4 +93,19 @@ - (void)array:(FirebaseIndexArray *)array
   [self.collectionView reloadItemsAtIndexPaths:@[path]];
 }
 
+#pragma mark - UICollectionViewDataSource
+
+- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section {
+  return self.array.count;
+}
+
+- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView
+                  cellForItemAtIndexPath:(NSIndexPath *)indexPath {
+  UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:self.identifier
+                                                                         forIndexPath:indexPath];
+  FIRDataSnapshot *snap = [self.array objectAtIndex:indexPath.item];
+  self.populateCell(cell, snap);
+  return cell;
+}
+
 @end

FirebaseDatabaseUI/FirebaseIndexTableViewDataSource.h

@@ -20,10 +20,24 @@
 
 NS_ASSUME_NONNULL_BEGIN
 
-@interface FirebaseIndexTableViewDataSource : NSObject
+@interface FirebaseIndexTableViewDataSource : NSObject <UITableViewDataSource>
 
 - (instancetype)init NS_UNAVAILABLE;
 
+/**
+ * Initializes a table view data source.
+ * @param indexQuery The Firebase query containing children of the data query.
+ * @param dataQuery The reference whose children correspond to the contents of the
+ *   index query. This reference's children's contents are served as teh contents 
+ *   of the table view that adopts this data source.
+ * @param tableView The table view that is populated by this data source. The
+ *   data source pulls updates from Firebase database, so it must maintain a reference
+ *   to the table view in order to update its contents as the database pushes updates.
+ *   The table view is not retained by its data source.
+ * @param cellIdentifier The cell reuse identifier used to dequeue reusable cells from
+ *   the table view.
+ * @param populateCell The closure invoked when populating a UITableViewCell (or subclass).
+ */
 - (instancetype)initWithIndex:(FIRDatabaseQuery *)indexQuery
                          data:(FIRDatabaseReference *)dataQuery
                     tableView:(UITableView *)tableView
@@ -33,7 +47,4 @@ NS_ASSUME_NONNULL_BEGIN
 
 @end
 
-@interface FirebaseIndexTableViewDataSource (TableViewDataSource) <UITableViewDataSource>
-@end
-
 NS_ASSUME_NONNULL_END

FirebaseDatabaseUI/FirebaseIndexTableViewDataSource.m

@@ -119,4 +119,8 @@ - (UITableViewCell *)tableView:(UITableView *)tableView
   return cell;
 }
 
+- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
+  return self.array.count;
+}
+
 @end