expose FUIIndexArray's indexes in data sources

FirebaseDatabaseUI/FUIIndexCollectionViewDataSource.h

@@ -57,8 +57,18 @@ didFailLoadAtIndex:(NSUInteger)index
  */
 @interface FUIIndexCollectionViewDataSource : NSObject <UICollectionViewDataSource>
 
+/**
+ * The delegate that should receive updates from this data source. Implement this delegate
+ * to handle load errors and successes.
+ */
 @property (nonatomic, readwrite, weak, nullable) id<FUIIndexCollectionViewDataSourceDelegate> delegate;
 
+/**
+ * The indexes that have finished loading in the data source. Returns an empty array if no indexes
+ * have loaded.
+ */
+@property (nonatomic, readonly, copy) NSArray<FIRDataSnapshot *> *indexes;
+
 - (instancetype)init NS_UNAVAILABLE;
 
 /**

FirebaseDatabaseUI/FUIIndexCollectionViewDataSource.m

@@ -50,6 +50,10 @@ - (instancetype)initWithIndex:(FIRDatabaseQuery *)indexQuery
   return self;
 }
 
+- (NSArray<FIRDataSnapshot *> *)indexes {
+  return self.array.indexes;
+}
+
 #pragma mark - FUIIndexArrayDelegate
 
 - (void)array:(FUIIndexArray *)array

FirebaseDatabaseUI/FUIIndexTableViewDataSource.h

@@ -58,10 +58,17 @@ didFailLoadAtIndex:(NSUInteger)index
 @interface FUIIndexTableViewDataSource : NSObject <UITableViewDataSource>
 
 /**
- * The delegate that will receive events from this data source.
+ * The delegate that should receive updates from this data source. Implement this delegate
+ * to handle load errors and successes.
  */
 @property (nonatomic, readwrite, weak, nullable) id<FUIIndexTableViewDataSourceDelegate> delegate;
 
+/**
+ * The indexes that have finished loading in the data source. Returns an empty array if no indexes
+ * have loaded.
+ */
+@property (nonatomic, readonly, copy) NSArray<FIRDataSnapshot *> *indexes;
+
 - (instancetype)init NS_UNAVAILABLE;
 
 /**

FirebaseDatabaseUI/FUIIndexTableViewDataSource.m

@@ -58,6 +58,10 @@ - (instancetype)initWithIndex:(FIRDatabaseQuery *)indexQuery
   return self;
 }
 
+- (NSArray<FIRDataSnapshot *> *)indexes {
+  return self.array.indexes;
+}
+
 #pragma mark - FUIIndexArrayDelegate 
 
 - (void)array:(FUIIndexArray *)array

FirebaseDatabaseUITests/FUIIndexCollectionViewDataSourceTest.m

@@ -93,6 +93,18 @@ - (void)tearDown {
   [super tearDown];
 }
 
+- (void)testItReturnsItsArraysIndexes {
+  NSArray *expectedIndexes = @[
+    [FUIFakeSnapshot snapWithKey:@"1" value:@(YES)],
+    [FUIFakeSnapshot snapWithKey:@"2" value:@(YES)],
+    [FUIFakeSnapshot snapWithKey:@"3" value:@(YES)],
+  ];
+
+  NSArray *indexes = self.dataSource.indexes;
+
+  XCTAssert([indexes isEqual:expectedIndexes], @"expected data source's indexes to equal its array's indexes");
+}
+
 - (void)testItPopulatesCells {
   UICollectionViewCell *cell = [self.dataSource collectionView:self.collectionView
                                         cellForItemAtIndexPath:[NSIndexPath indexPathForItem:0 inSection:0]];

FirebaseDatabaseUITests/FUIIndexTableViewDataSourceTest.m

@@ -88,6 +88,18 @@ - (void)tearDown {
   [super tearDown];
 }
 
+- (void)testItReturnsItsArraysIndexes {
+  NSArray *expectedIndexes = @[
+    [FUIFakeSnapshot snapWithKey:@"1" value:@(YES)],
+    [FUIFakeSnapshot snapWithKey:@"2" value:@(YES)],
+    [FUIFakeSnapshot snapWithKey:@"3" value:@(YES)],
+  ];
+
+  NSArray *indexes = self.dataSource.indexes;
+
+  XCTAssert([indexes isEqual:expectedIndexes], @"expected data source's indexes to equal its array's indexes");
+}
+
 - (void)testItPopulatesCells {
   UITableViewCell *cell = [self.dataSource tableView:self.tableView
                                cellForRowAtIndexPath:[NSIndexPath indexPathForRow:0 inSection:0]];