add syntax shorthand for data sources

Author: morganchen12

FirebaseDatabaseUI/FirebaseCollectionViewDataSource.h

@@ -83,4 +83,24 @@ NS_ASSUME_NONNULL_BEGIN
 
 @end
 
+@interface UICollectionView (FirebaseCollectionViewDataSource)
+
+/**
+ * Creates a data source, attaches it to the collection view, and returns it.
+ * The returned data source is not retained by the collection view and must be
+ * retained or it will be deallocated while still in use by the collection view.
+ * @param query A Firebase database query to bind the collection view to.
+ * @param populateCell A closure used by the data source to create the cells
+ *   displayed in the collection view. The closure is retained by the returned
+ *   data source.
+ * @return The created data source. This value must be retained while the collection
+ *   view is in use.
+ */
+- (FirebaseCollectionViewDataSource *)bindToQuery:(FIRDatabaseQuery *)query
+                                     populateCell:(UICollectionViewCell *(^)(UICollectionView *collectionView,
+                                                                             NSIndexPath *indexPath,
+                                                                             FIRDataSnapshot *object))populateCell __attribute__((warn_unused_result));
+
+@end
+
 NS_ASSUME_NONNULL_END

FirebaseDatabaseUI/FirebaseCollectionViewDataSource.m

@@ -84,3 +84,17 @@ - (NSInteger)collectionView:(nonnull UICollectionView *)collectionView
 }
 
 @end
+
+@implementation UICollectionView (FirebaseCollectionViewDataSource)
+
+- (FirebaseCollectionViewDataSource *)bindToQuery:(FIRDatabaseQuery *)query
+                                     populateCell:(UICollectionViewCell *(^)(UICollectionView *,
+                                                                             NSIndexPath *,
+                                                                             FIRDataSnapshot *))populateCell {
+  FirebaseCollectionViewDataSource *dataSource =
+    [[FirebaseCollectionViewDataSource alloc] initWithQuery:query view:self populateCell:populateCell];
+  self.dataSource = dataSource;
+  return dataSource;
+}
+
+@end

FirebaseDatabaseUI/FirebaseTableViewDataSource.h

@@ -74,4 +74,24 @@ NS_ASSUME_NONNULL_BEGIN
 
 @end
 
+@interface UITableView (FirebaseTableViewDataSource)
+
+/**
+ * Creates a data source, attaches it to the table view, and returns it.
+ * The returned data source is not retained by the table view and must be
+ * retained or it will be deallocated while still in use by the table view.
+ * @param query A Firebase database query to bind the table view to.
+ * @param populateCell A closure used by the data source to create the cells
+ *   displayed in the table view. The closure is retained by the returned
+ *   data source.
+ * @return The created data source. This value must be retained while the table
+ *   view is in use.
+ */
+- (FirebaseTableViewDataSource *)bindToQuery:(FIRDatabaseQuery *)query
+                                populateCell:(UITableViewCell *(^)(UITableView *tableView,
+                                                                   NSIndexPath *indexPath,
+                                                                   FIRDataSnapshot *object))populateCell __attribute__((warn_unused_result));
+
+@end
+
 NS_ASSUME_NONNULL_END

FirebaseDatabaseUI/FirebaseTableViewDataSource.m

@@ -94,3 +94,17 @@ - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger
 }
 
 @end
+
+@implementation UITableView (FirebaseTableViewDataSource)
+
+- (FirebaseTableViewDataSource *)bindToQuery:(FIRDatabaseQuery *)query
+                                populateCell:(UITableViewCell *(^)(UITableView *tableView,
+                                                                   NSIndexPath *indexPath,
+                                                                   FIRDataSnapshot *snap))populateCell {
+  FirebaseTableViewDataSource *dataSource =
+    [[FirebaseTableViewDataSource alloc] initWithQuery:query view:self populateCell:populateCell];
+  self.dataSource = dataSource;
+  return dataSource;
+}
+
+@end

FirebaseDatabaseUITests/FirebaseCollectionViewDataSourceTest.m

@@ -44,14 +44,14 @@ - (void)setUp {
   self.observable = [[FUITestObservable alloc] init];
   // Horrible abuse of type system, knowing that the initializer passes the observable straight to
   // FirebaseArray anyway.
-  self.dataSource = [[FirebaseCollectionViewDataSource alloc] initWithQuery:(FIRDatabaseReference *)self.observable
-                                                                       view:self.collectionView
-                                                               populateCell:^UICollectionViewCell *(UICollectionView *collectionView, NSIndexPath *indexPath, FIRDataSnapshot *object) {
+  self.dataSource = [self.collectionView bindToQuery:(FIRDatabaseReference *)self.observable
+                                        populateCell:^UICollectionViewCell *(UICollectionView *collectionView,
+                                                                             NSIndexPath *indexPath,
+                                                                             FIRDataSnapshot *object) {
     UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:kTestReuseIdentifier forIndexPath:indexPath];
     cell.accessibilityValue = object.key;
     return cell;
   }];
-  self.collectionView.dataSource = self.dataSource;
 
   // Removing this NSLog causes the tests to crash since `numberOfItemsInSection`
   // actually pulls updates from the data source or something

FirebaseDatabaseUITests/FirebaseTableViewDataSourceTest.m

@@ -44,17 +44,15 @@ - (void)setUp {
   self.observable = [[FUITestObservable alloc] init];
   // Horrible abuse of type system, knowing that the initializer passes the observable straight to
   // FirebaseArray anyway.
-  self.dataSource = [[FirebaseTableViewDataSource alloc] initWithQuery:(FIRDatabaseQuery *)self.observable
-                                                                  view:self.tableView
-                                                          populateCell:^UITableViewCell *(UITableView *tableView,
-                                                                                          NSIndexPath *indexPath,
-                                                                                          FIRDataSnapshot *object) {
+  self.dataSource = [self.tableView bindToQuery:(FIRDatabaseReference *)self.observable
+                                   populateCell:^UITableViewCell *(UITableView *tableView,
+                                                                   NSIndexPath *indexPath,
+                                                                   FIRDataSnapshot *object) {
     UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:kTestReuseIdentifier];
     cell.accessibilityValue = object.key;
     return cell;
   }];
-  self.tableView.dataSource = self.dataSource;
-  
+
   [self.observable populateWithCount:10];
 }