implement error handling methods for indexed data sources

Author: morganchen12

FirebaseDatabaseUI/FirebaseIndexCollectionViewDataSource.h

@@ -20,8 +20,41 @@
 
 NS_ASSUME_NONNULL_BEGIN
 
+@class FirebaseIndexCollectionViewDataSource;
+
+@protocol FirebaseIndexCollectionViewDataSourceDelegate <NSObject>
+@optional
+
+/**
+ * Called when an individual reference responsible for populating one cell
+ * of the collection view has raised an error. This error is unrecoverable, but
+ * does not have any effect on the contents of other cells.
+ * @param dataSource The FirebaseIndexCollectionViewDataSource raising the error.
+ * @param ref The reference that failed to load.
+ * @param index The index (i.e. row) of the query that failed to load.
+ * @param error The error that occurred.
+ */
+- (void)dataSource:(FirebaseIndexCollectionViewDataSource *)dataSource
+         reference:(FIRDatabaseReference *)ref
+didFailLoadAtIndex:(NSUInteger)index
+         withError:(NSError *)error;
+
+/**
+ * Called when the index query used to initialize this data source raised an error.
+ * This error is unrecoverable, and likely indicates a bad index query.
+ * @param dataSource The FirebaseIndexCollectionViewDataSource raising the error.
+ * @param error The error that occurred.
+ */
+- (void)dataSource:(FirebaseIndexCollectionViewDataSource *)dataSource
+  indexQueryDidFailWithError:(NSError *)error;
+
+@end
+
+
 @interface FirebaseIndexCollectionViewDataSource : NSObject <UICollectionViewDataSource>
 
+@property (nonatomic, readwrite, weak, nullable) id<FirebaseIndexCollectionViewDataSourceDelegate> delegate;
+
 - (instancetype)init NS_UNAVAILABLE;
 
 /**
@@ -33,7 +66,7 @@ NS_ASSUME_NONNULL_BEGIN
  * @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.
+ *   The collection 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).

FirebaseDatabaseUI/FirebaseIndexCollectionViewDataSource.m

@@ -51,8 +51,19 @@ - (instancetype)initWithIndex:(FIRDatabaseQuery *)indexQuery
 
 #pragma mark - FirebaseIndexArrayDelegate
 
+- (void)array:(FirebaseIndexArray *)array
+    reference:(FIRDatabaseReference *)ref
+      atIndex:(NSUInteger)index
+didFailLoadWithError:(NSError *)error {
+  if ([self.delegate respondsToSelector:@selector(dataSource:reference:didFailLoadAtIndex:withError:)]) {
+    [self.delegate dataSource:self reference:ref didFailLoadAtIndex:index withError:error];
+  }
+}
+
 - (void)array:(FirebaseIndexArray *)array queryCancelledWithError:(NSError *)error {
-  // TODO: implement actual error handling
+  if ([self.delegate respondsToSelector:@selector(dataSource:indexQueryDidFailWithError:)]) {
+    [self.delegate dataSource:self indexQueryDidFailWithError:error];
+  }
   NSLog(@"%@ Error: Firebase query cancelled with error %@", self, error);
 }
 

FirebaseDatabaseUI/FirebaseIndexTableViewDataSource.h

@@ -20,8 +20,43 @@
 
 NS_ASSUME_NONNULL_BEGIN
 
+@class FirebaseIndexTableViewDataSource;
+
+@protocol FirebaseIndexTableViewDataSourceDelegate <NSObject>
+@optional
+
+/**
+ * Called when an individual reference responsible for populating one cell
+ * of the table view has raised an error. This error is unrecoverable, but
+ * does not have any effect on the contents of other cells.
+ * @param dataSource The FirebaseIndexTableViewDataSource raising the error.
+ * @param ref The reference that failed to load.
+ * @param index The index (i.e. row) of the query that failed to load.
+ * @param error The error that occurred.
+ */
+- (void)dataSource:(FirebaseIndexTableViewDataSource *)dataSource
+         reference:(FIRDatabaseReference *)ref
+didFailLoadAtIndex:(NSUInteger)index
+         withError:(NSError *)error;
+
+/**
+ * Called when the index query used to initialize this data source raised an error.
+ * This error is unrecoverable, and likely indicates a bad index query.
+ * @param dataSource The FirebaseIndexTableViewDataSource raising the error.
+ * @param error The error that occurred.
+ */
+- (void)dataSource:(FirebaseIndexTableViewDataSource *)dataSource
+  indexQueryDidFailWithError:(NSError *)error;
+
+@end
+
 @interface FirebaseIndexTableViewDataSource : NSObject <UITableViewDataSource>
 
+/**
+ * The delegate that will receive events from this data source.
+ */
+@property (nonatomic, readwrite, weak, nullable) id<FirebaseIndexTableViewDataSourceDelegate> delegate;
+
 - (instancetype)init NS_UNAVAILABLE;
 
 /**
@@ -42,6 +77,7 @@ NS_ASSUME_NONNULL_BEGIN
                          data:(FIRDatabaseReference *)dataQuery
                     tableView:(UITableView *)tableView
           cellReuseIdentifier:(NSString *)cellIdentifier
+                     delegate:(nullable id<FirebaseIndexTableViewDataSourceDelegate>)delegate
                  populateCell:(void (^)(UITableViewCell *cell,
                                         FIRDataSnapshot *_Nullable))populateCell NS_DESIGNATED_INITIALIZER;
 

FirebaseDatabaseUI/FirebaseIndexTableViewDataSource.m

@@ -42,6 +42,7 @@ - (instancetype)initWithIndex:(FIRDatabaseQuery *)indexQuery
                          data:(FIRDatabaseReference *)dataQuery
                     tableView:(UITableView *)tableView
           cellReuseIdentifier:(NSString *)cellIdentifier
+                     delegate:(nullable id<FirebaseIndexTableViewDataSourceDelegate>)delegate
                  populateCell:(nonnull void (^)(UITableViewCell *cell,
                                                 FIRDataSnapshot *data))populateCell {
   self = [super init];
@@ -59,8 +60,19 @@ - (instancetype)initWithIndex:(FIRDatabaseQuery *)indexQuery
 
 #pragma mark - FirebaseIndexArrayDelegate 
 
+- (void)array:(FirebaseIndexArray *)array
+    reference:(FIRDatabaseReference *)ref
+      atIndex:(NSUInteger)index
+didFailLoadWithError:(NSError *)error {
+  if ([self.delegate respondsToSelector:@selector(dataSource:reference:didFailLoadAtIndex:withError:)]) {
+    [self.delegate dataSource:self reference:ref didFailLoadAtIndex:index withError:error];
+  }
+}
+
 - (void)array:(FirebaseIndexArray *)array queryCancelledWithError:(NSError *)error {
-  // TODO: implement actual error handling
+  if ([self.delegate respondsToSelector:@selector(dataSource:indexQueryDidFailWithError:)]) {
+    [self.delegate dataSource:self indexQueryDidFailWithError:error];
+  }
   NSLog(@"%@ Error: Firebase query cancelled with error %@", self, error);
 }