cheat at subclassing to expose less public mutability

Author: morganchen12

FirebaseDatabaseUI/FUIArray.h

@@ -118,40 +118,36 @@ NS_ASSUME_NONNULL_BEGIN
 
 /**
  * Called when the Firebase query sends a FIRDataEventTypeChildAdded event. Override this
- * to provide custom insertion logic.
+ * to provide custom insertion logic. Don't call this method directly.
  * @param snap The snapshot that was inserted.
  * @param previous The key of the sibling preceding the inserted snapshot.
  */
 - (void)insertSnapshot:(FIRDataSnapshot *)snap withPreviousChildKey:(nullable NSString *)previous;
 
 /**
  * Called when the Firebase query sends a FIRDataEventTypeChildRemoved event. Override this
- * to provide custom removal logic.
+ * to provide custom removal logic. Don't call this method directly.
  * @param snap The snapshot that was removed.
  * @param previous The key of the sibling preceding the removed snapshot.
  */
 - (void)removeSnapshot:(FIRDataSnapshot *)snap withPreviousChildKey:(nullable NSString *)previous;
 
 /**
  * Called when the Firebase query sends a FIRDataEventTypeChildChanged event. Override this
- * to provide custom on change logic.
+ * to provide custom on change logic. Don't call this method directly.
  * @param snap The snapshot whose value was changed.
  * @param previous The key of the sibling preceding the changed snapshot.
  */
 - (void)changeSnapshot:(FIRDataSnapshot *)snap withPreviousChildKey:(nullable NSString *)previous;
 
 /**
  * Called when the Firebase query sends a FIRDataEventTypeChildMoved event. Override this
- * to provide custom move logic.
+ * to provide custom move logic. Don't call this method directly.
  * @param snap The snapshot that was moved.
  * @param previous The key of the sibling preceding the moved snapshot at its new location.
  */
 - (void)moveSnapshot:(FIRDataSnapshot *)snap withPreviousChildKey:(nullable NSString *)previous;
 
-- (void)removeSnapshotAtIndex:(NSUInteger)index;
-- (void)insertSnapshot:(FIRDataSnapshot *)snap atIndex:(NSUInteger)index;
-- (void)addSnapshot:(FIRDataSnapshot *)snap;
-
 @end
 
 NS_ASSUME_NONNULL_END

FirebaseDatabaseUI/FUISortedArray.m

@@ -23,6 +23,11 @@ @interface FUISortedArray ()
  */
 @property (nonatomic, copy, nonnull) NSComparisonResult (^sortDescriptor)(FIRDataSnapshot *, FIRDataSnapshot *);
 
+/**
+ * The backing collection that holds all of the array's data.
+ */
+@property (strong, nonatomic) NSMutableArray<FIRDataSnapshot *> *snapshots;
+
 /**
  * A set containing the query observer handles that should be released when
  * this array is freed.
@@ -32,6 +37,9 @@ @interface FUISortedArray ()
 @end
 
 @implementation FUISortedArray
+// Cheating at subclassing, but this @dynamic avoids
+// duplicating storage without exposing mutability publicly
+@dynamic snapshots;
 
 - (instancetype)initWithQuery:(FIRDatabaseQuery *)query
                      delegate:(id<FUICollectionDelegate>)delegate
@@ -57,7 +65,7 @@ - (void)removeSnapshot:(FIRDataSnapshot *)snap withPreviousChildKey:(NSString *)
   NSInteger index = [self indexForKey:snap.key];
   if (index == NSNotFound) { /* error */ return; }
 
-  [self removeSnapshotAtIndex:index];
+  [self.snapshots removeObjectAtIndex:index];
   if ([self.delegate respondsToSelector:@selector(array:didRemoveObject:atIndex:)]) {
     [self.delegate array:self didRemoveObject:snap atIndex:index];
   }
@@ -71,7 +79,7 @@ - (void)changeSnapshot:(FIRDataSnapshot *)snap withPreviousChildKey:(NSString *)
 
   // Since changes can change ordering, model changes as a deletion and an insertion.
   FIRDataSnapshot *removed = [self snapshotAtIndex:index];
-  [self removeSnapshotAtIndex:index];
+  [self.snapshots removeObjectAtIndex:index];
   if ([self.delegate respondsToSelector:@selector(array:didRemoveObject:atIndex:)]) {
     [self.delegate array:self didRemoveObject:removed atIndex:index];
   }
@@ -92,29 +100,29 @@ - (NSArray *)items {
 
 - (NSInteger)insertSnapshot:(FIRDataSnapshot *)snapshot {
   if (self.count == 0) {
-    [self addSnapshot:snapshot];
+    [self.snapshots addObject:snapshot];
     return 0;
   }
   if (self.count == 1) {
     NSComparisonResult result = self.sortDescriptor(snapshot, [self snapshotAtIndex:0]);
     switch (result) {
       case NSOrderedDescending:
-        [self addSnapshot:snapshot];
+        [self.snapshots addObject:snapshot];
         return 1;
       default:
-        [self insertSnapshot:snapshot atIndex:0];
+        [self.snapshots insertObject:snapshot atIndex:0];
         return 0;
     }
   }
 
   NSInteger index = self.count / 2;
   while (index >= 0 && index <= self.count) {
     if (index == 0) {
-      [self insertSnapshot:snapshot atIndex:index];
+      [self.snapshots insertObject:snapshot atIndex:index];
       return 0;
     }
     if (index == self.count) {
-      [self addSnapshot:snapshot];
+      [self.snapshots addObject:snapshot];
       return index;
     }
 
@@ -136,7 +144,7 @@ - (NSInteger)insertSnapshot:(FIRDataSnapshot *)snapshot {
       NSAssert(NO, @"FUISortedArray %@'s sort descriptor returned inconsistent results!", self);
     } else {
       // good
-      [self insertSnapshot:snapshot atIndex:index];
+      [self.snapshots insertObject:snapshot atIndex:index];
       return index;
     }
   }