add sorted firebase collection

Author: morganchen12

FirebaseDatabaseUI/FUIArray.h

@@ -20,7 +20,7 @@
 
 @import FirebaseDatabase;
 
-#import "FUIArrayDelegate.h"
+#import "FUICollection.h"
 
 NS_ASSUME_NONNULL_BEGIN
 
@@ -43,23 +43,23 @@ NS_ASSUME_NONNULL_BEGIN
  * query. It is useful for building custom data structures or sources, and provides the base for
  * FirebaseDataSource.
  */
-@interface FUIArray : NSObject
+@interface FUIArray : NSObject <FUICollection>
 
 /**
  * The delegate object that array changes are surfaced to, which conforms to the
- * @c FUIArrayDelegate protocol.
+ * @c FUICollectionDelegate protocol.
  */
-@property(weak, nonatomic, nullable) id<FUIArrayDelegate> delegate;
+@property (weak, nonatomic, nullable) id<FUICollectionDelegate> delegate;
 
 /**
  * The query on a Firebase reference that provides data to populate the array.
  */
-@property(strong, nonatomic) id<FIRDataObservable> query;
+@property (strong, nonatomic) id<FIRDataObservable> query;
 
 /**
  * The number of objects in the array.
  */
-@property(nonatomic, readonly) NSUInteger count;
+@property (nonatomic, readonly) NSUInteger count;
 
 /**
  * The items currently in the array.
@@ -83,9 +83,9 @@ NS_ASSUME_NONNULL_BEGIN
 /**
  * Returns an object at a specific index in the array.
  * @param index The index of the item to retrieve
- * @return The object at the given index
+ * @return The snapshot at the given index
  */
-- (id)objectAtIndex:(NSUInteger)index;
+- (FIRDataSnapshot *)snapshotAtIndex:(NSInteger)index;
 
 /**
  * Returns a Firebase reference for an object at a specific index in the array.

FirebaseDatabaseUI/FUIArrayDelegate.h renamed to FirebaseDatabaseUI/FUICollection.h

@@ -18,13 +18,33 @@
 
 // clang-format on
 
+@import Foundation;
+
 @class FUIArray;
+@protocol FUICollectionDelegate;
+
+NS_ASSUME_NONNULL_BEGIN
+
+@protocol FUICollection <NSObject>
+
+@property (nonatomic, readonly, copy) NSArray<FIRDataSnapshot *> *items;
+
+@property (weak, nonatomic, nullable) id<FUICollectionDelegate> delegate;
+
+/**
+ * The number of objects in the FirebaseArray.
+ */
+@property (nonatomic, readonly) NSUInteger count;
+
+- (FIRDataSnapshot *)snapshotAtIndex:(NSInteger)index;
+
+@end
 
 /**
  * A protocol to allow instances of FUIArray to raise events through a
  * delegate. Raises all Firebase events except FIRDataEventTypeValue.
  */
-@protocol FUIArrayDelegate<NSObject>
+@protocol FUICollectionDelegate<NSObject>
 
 @optional
 
@@ -35,7 +55,7 @@
  * @param object The object added to the FUIArray
  * @param index The index the child was added at
  */
-- (void)array:(FUIArray *)array didAddObject:(id)object atIndex:(NSUInteger)index;
+- (void)array:(id<FUICollection>)array didAddObject:(id)object atIndex:(NSUInteger)index;
 
 /**
  * Delegate method which is called whenever an object is changed in an
@@ -44,7 +64,7 @@
  * @param object The object that changed in the FUIArray
  * @param index The index the child was changed at
  */
-- (void)array:(FUIArray *)array didChangeObject:(id)object atIndex:(NSUInteger)index;
+- (void)array:(id<FUICollection>)array didChangeObject:(id)object atIndex:(NSUInteger)index;
 
 /**
  * Delegate method which is called whenever an object is removed from an
@@ -53,7 +73,7 @@
  * @param object The object removed from the FUIArray
  * @param index The index the child was removed at
  */
-- (void)array:(FUIArray *)array didRemoveObject:(id)object atIndex:(NSUInteger)index;
+- (void)array:(id<FUICollection>)array didRemoveObject:(id)object atIndex:(NSUInteger)index;
 
 /**
  * Delegate method which is called whenever an object is moved within a
@@ -63,12 +83,14 @@
  * @param fromIndex The index the child is being moved from
  * @param toIndex The index the child is being moved to
  */
-- (void)array:(FUIArray *)array didMoveObject:(id)object fromIndex:(NSUInteger)fromIndex toIndex:(NSUInteger)toIndex;
+- (void)array:(id<FUICollection>)array didMoveObject:(id)object fromIndex:(NSUInteger)fromIndex toIndex:(NSUInteger)toIndex;
 
 /**
  * Delegate method which is called whenever the backing query is canceled.
  * @param error the error that was raised
  */
-- (void)array:(FUIArray *)array queryCancelledWithError:(NSError *)error;
+- (void)array:(id<FUICollection>)array queryCancelledWithError:(NSError *)error;
 
 @end
+
+NS_ASSUME_NONNULL_END

FirebaseDatabaseUI/FUICollectionViewDataSource.m

@@ -40,7 +40,7 @@ - (instancetype)initWithQuery:(FIRDatabaseQuery *)query
   return self;
 }
 
-#pragma mark - FUIArrayDelegate methods
+#pragma mark - FUICollectionDelegate methods
 
 - (void)array:(FUIArray *)array didAddObject:(id)object atIndex:(NSUInteger)index {
   [self.collectionView

FirebaseDatabaseUI/FUIDataSource.h

@@ -32,7 +32,7 @@
  * subclasses need as well as several methods that pass through to the instance
  * of FirebaseArray.
  */
-@interface FUIDataSource : NSObject<FUIArrayDelegate>
+@interface FUIDataSource : NSObject<FUICollectionDelegate>
 
 /**
  * The items in the data source.
@@ -49,9 +49,9 @@
 - (instancetype)init NS_UNAVAILABLE;
 
 /**
- * Pass through of [FirebaseArray objectAtIndex:].
+ * Pass through of [FirebaseArray snapshotAtIndex:].
  */
-- (id)objectAtIndex:(NSUInteger)index;
+- (FIRDataSnapshot *)objectAtIndex:(NSUInteger)index;
 
 /**
  * Pass through of [FirebaseArray refForIndex:].

FirebaseDatabaseUI/FUIDataSource.m

@@ -54,8 +54,8 @@ - (NSUInteger)count {
   return self.array.count;
 }
 
-- (id)objectAtIndex:(NSUInteger)index {
-  return [self.array objectAtIndex:index];
+- (FIRDataSnapshot *)objectAtIndex:(NSUInteger)index {
+  return [self.array snapshotAtIndex:index];
 }
 
 - (FIRDatabaseReference *)refForIndex:(NSUInteger)index {
@@ -66,7 +66,7 @@ - (void)cancelWithBlock:(void (^)(NSError *))block {
   self.cancelBlock = block;
 }
 
-#pragma mark - FUIArrayDelegate methods
+#pragma mark - FUICollectionDelegate methods
 
 - (void)canceledWithError:(NSError *)error {
   if (self.cancelBlock != nil) {

FirebaseDatabaseUI/FUISortedArray.h

@@ -0,0 +1,43 @@
+//
+//  Copyright (c) 2016 Google Inc.
+//
+//  Licensed under the Apache License, Version 2.0 (the "License");
+//  you may not use this file except in compliance with the License.
+//  You may obtain a copy of the License at
+//
+//  http://www.apache.org/licenses/LICENSE-2.0
+//
+//  Unless required by applicable law or agreed to in writing, software
+//  distributed under the License is distributed on an "AS IS" BASIS,
+//  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+//  See the License for the specific language governing permissions and
+//  limitations under the License.
+//
+
+@import FirebaseDatabase;
+
+#import <FirebaseDatabaseUI/FirebaseDatabaseUI.h>
+
+NS_ASSUME_NONNULL_BEGIN
+
+@interface FUISortedArray : NSObject <FUICollection>
+
+@property (nonatomic, readonly, copy) NSArray<FIRDataSnapshot *> *items;
+
+@property (nonatomic, weak, readwrite, nullable) id<FUICollectionDelegate> delegate;
+
+- (instancetype)init NS_UNAVAILABLE;
+
+- (instancetype)initWithQuery:(id<FIRDataObservable>)query
+                     delegate:(nullable id<FUICollectionDelegate>)delegate
+               sortDescriptor:(NSComparisonResult (^)(FIRDataSnapshot *left,
+                                                      FIRDataSnapshot *right))sortDescriptor NS_DESIGNATED_INITIALIZER;
+
+- (void)observeQuery;
+- (void)invalidate;
+
+- (FIRDataSnapshot *)snapshotAtIndex:(NSInteger)index;
+
+@end
+
+NS_ASSUME_NONNULL_END