diff --git a/engine/src/flutter/shell/platform/darwin/ios/framework/Source/FlutterEngine.mm b/engine/src/flutter/shell/platform/darwin/ios/framework/Source/FlutterEngine.mm
index 8ab4cf61c0..85f1ba5519 100644
--- a/engine/src/flutter/shell/platform/darwin/ios/framework/Source/FlutterEngine.mm
+++ b/engine/src/flutter/shell/platform/darwin/ios/framework/Source/FlutterEngine.mm
@@ -84,7 +84,6 @@ NSString* const FlutterDefaultInitialRoute = nil;
 
 #pragma mark - Internal constants
 
-NSString* const kFlutterEngineWillDealloc = @"FlutterEngineWillDealloc";
 NSString* const kFlutterKeyDataChannel = @"flutter/keydata";
 static constexpr int kNumProfilerSamplesPerSec = 5;
 
@@ -282,10 +281,6 @@ static constexpr int kNumProfilerSamplesPerSec = 5;
     }
   }];
 
-  [[NSNotificationCenter defaultCenter] postNotificationName:kFlutterEngineWillDealloc
-                                                      object:self
-                                                    userInfo:nil];
-
   // nil out weak references.
   // TODO(cbracken): https://github.com/flutter/flutter/issues/156222
   // Ensure that FlutterEngineRegistrar is using weak pointers, then eliminate this code.
diff --git a/engine/src/flutter/shell/platform/darwin/ios/framework/Source/FlutterEngineGroup.mm b/engine/src/flutter/shell/platform/darwin/ios/framework/Source/FlutterEngineGroup.mm
index b274475f7e..3202c195d9 100644
--- a/engine/src/flutter/shell/platform/darwin/ios/framework/Source/FlutterEngineGroup.mm
+++ b/engine/src/flutter/shell/platform/darwin/ios/framework/Source/FlutterEngineGroup.mm
@@ -12,7 +12,7 @@ FLUTTER_ASSERT_ARC
 
 @interface FlutterEngineGroup ()
 @property(nonatomic, copy) NSString* name;
-@property(nonatomic, strong) NSMutableArray<NSValue*>* engines;
+@property(nonatomic, strong) NSPointerArray* engines;
 @property(nonatomic, copy) FlutterDartProject* project;
 @property(nonatomic, assign) NSUInteger enginesCreatedCount;
 @end
@@ -23,7 +23,7 @@ FLUTTER_ASSERT_ARC
   self = [super init];
   if (self) {
     _name = [name copy];
-    _engines = [[NSMutableArray<NSValue*> alloc] init];
+    _engines = [NSPointerArray weakObjectsPointerArray];
     _project = project;
   }
   return self;
@@ -51,6 +51,12 @@ FLUTTER_ASSERT_ARC
   NSArray<NSString*>* entrypointArgs = options.entrypointArgs;
 
   FlutterEngine* engine;
+  // NSPointerArray is clever and assumes that unless a mutation operation has occurred on it that
+  // has set one of its values to nil, nothing could have changed and it can skip compaction.
+  // That's reasonable behaviour on a regular NSPointerArray but not for a weakObjectPointerArray.
+  // As a workaround, we mutate it first. See: http://www.openradar.me/15396578
+  [self.engines addPointer:nil];
+  [self.engines compact];
   if (self.engines.count <= 0) {
     engine = [self makeEngine];
     [engine runWithEntrypoint:entrypoint
@@ -58,20 +64,13 @@ FLUTTER_ASSERT_ARC
                  initialRoute:initialRoute
                entrypointArgs:entrypointArgs];
   } else {
-    FlutterEngine* spawner = (FlutterEngine*)[self.engines[0] pointerValue];
+    FlutterEngine* spawner = (__bridge FlutterEngine*)[self.engines pointerAtIndex:0];
     engine = [spawner spawnWithEntrypoint:entrypoint
                                libraryURI:libraryURI
                              initialRoute:initialRoute
                            entrypointArgs:entrypointArgs];
   }
-  // TODO(cbracken): https://github.com/flutter/flutter/issues/155943
-  [self.engines addObject:[NSValue valueWithPointer:(__bridge void*)engine]];
-
-  NSNotificationCenter* center = [NSNotificationCenter defaultCenter];
-  [center addObserver:self
-             selector:@selector(onEngineWillBeDealloced:)
-                 name:kFlutterEngineWillDealloc
-               object:engine];
+  [self.engines addPointer:(__bridge void*)engine];
 
   return engine;
 }
@@ -82,9 +81,4 @@ FLUTTER_ASSERT_ARC
   return [[FlutterEngine alloc] initWithName:engineName project:self.project];
 }
 
-- (void)onEngineWillBeDealloced:(NSNotification*)notification {
-  // TODO(cbracken): https://github.com/flutter/flutter/issues/155943
-  [self.engines removeObject:[NSValue valueWithPointer:(__bridge void*)notification.object]];
-}
-
 @end
diff --git a/engine/src/flutter/shell/platform/darwin/ios/framework/Source/FlutterEngineGroupTest.mm b/engine/src/flutter/shell/platform/darwin/ios/framework/Source/FlutterEngineGroupTest.mm
index 77929ea6b4..2d25d457c0 100644
--- a/engine/src/flutter/shell/platform/darwin/ios/framework/Source/FlutterEngineGroupTest.mm
+++ b/engine/src/flutter/shell/platform/darwin/ios/framework/Source/FlutterEngineGroupTest.mm
@@ -37,11 +37,16 @@ FLUTTER_ASSERT_ARC
 }
 
 - (void)testDeleteLastEngine {
+  __weak FlutterEngine* weakSpawner;
   FlutterEngineGroup* group = [[FlutterEngineGroup alloc] initWithName:@"foo" project:nil];
   @autoreleasepool {
     FlutterEngine* spawner = [group makeEngineWithEntrypoint:nil libraryURI:nil];
+    weakSpawner = spawner;
     XCTAssertNotNil(spawner);
+    XCTAssertNotNil(weakSpawner);
   }
+  XCTAssertNil(weakSpawner);
+
   FlutterEngine* spawnee = [group makeEngineWithEntrypoint:nil libraryURI:nil];
   XCTAssertNotNil(spawnee);
 }
diff --git a/engine/src/flutter/shell/platform/darwin/ios/framework/Source/FlutterEngineTest.mm b/engine/src/flutter/shell/platform/darwin/ios/framework/Source/FlutterEngineTest.mm
index ddc18c5429..58bfbdf160 100644
--- a/engine/src/flutter/shell/platform/darwin/ios/framework/Source/FlutterEngineTest.mm
+++ b/engine/src/flutter/shell/platform/darwin/ios/framework/Source/FlutterEngineTest.mm
@@ -262,23 +262,6 @@ FLUTTER_ASSERT_ARC
   XCTAssertNotNil(spawn);
 }
 
-- (void)testDeallocNotification {
-  XCTestExpectation* deallocNotification = [self expectationWithDescription:@"deallocNotification"];
-  NSNotificationCenter* center = [NSNotificationCenter defaultCenter];
-  id<NSObject> observer;
-  @autoreleasepool {
-    FlutterEngine* engine = [[FlutterEngine alloc] initWithName:@"foobar"];
-    observer = [center addObserverForName:kFlutterEngineWillDealloc
-                                   object:engine
-                                    queue:[NSOperationQueue mainQueue]
-                               usingBlock:^(NSNotification* note) {
-                                 [deallocNotification fulfill];
-                               }];
-  }
-  [self waitForExpectations:@[ deallocNotification ]];
-  [center removeObserver:observer];
-}
-
 - (void)testSetHandlerAfterRun {
   FlutterEngine* engine = [[FlutterEngine alloc] initWithName:@"foobar"];
   XCTestExpectation* gotMessage = [self expectationWithDescription:@"gotMessage"];
diff --git a/engine/src/flutter/shell/platform/darwin/ios/framework/Source/FlutterEngine_Internal.h b/engine/src/flutter/shell/platform/darwin/ios/framework/Source/FlutterEngine_Internal.h
index 489dfd38c4..6f954adbcb 100644
--- a/engine/src/flutter/shell/platform/darwin/ios/framework/Source/FlutterEngine_Internal.h
+++ b/engine/src/flutter/shell/platform/darwin/ios/framework/Source/FlutterEngine_Internal.h
@@ -29,8 +29,6 @@
 
 NS_ASSUME_NONNULL_BEGIN
 
-extern NSString* const kFlutterEngineWillDealloc;
-
 @interface FlutterEngine () <FlutterViewEngineDelegate>
 
 - (flutter::Shell&)shell;
diff --git a/engine/src/flutter/shell/platform/darwin/ios/framework/Source/FlutterEngine_Test.h b/engine/src/flutter/shell/platform/darwin/ios/framework/Source/FlutterEngine_Test.h
index 238f6528aa..104ab9aef5 100644
--- a/engine/src/flutter/shell/platform/darwin/ios/framework/Source/FlutterEngine_Test.h
+++ b/engine/src/flutter/shell/platform/darwin/ios/framework/Source/FlutterEngine_Test.h
@@ -11,8 +11,6 @@
 #import "flutter/shell/platform/darwin/ios/rendering_api_selection.h"
 #include "flutter/shell/platform/embedder/embedder.h"
 
-extern NSString* const kFlutterEngineWillDealloc;
-
 @class FlutterBinaryMessengerRelay;
 
 namespace flutter {