limits on identifiers

packages/webview_flutter/webview_flutter/example/ios/Flutter/AppFrameworkInfo.plist

@@ -21,6 +21,6 @@
   <key>CFBundleVersion</key>
   <string>1.0</string>
   <key>MinimumOSVersion</key>
-  <string>9.0</string>
+  <string>11.0</string>
 </dict>
 </plist>

packages/webview_flutter/webview_flutter/example/ios/Podfile

@@ -1,5 +1,5 @@
 # Uncomment this line to define a global platform for your project
-# platform :ios, '9.0'
+# platform :ios, '11.0'
 
 # CocoaPods analytics sends network stats synchronously affecting flutter build latency.
 ENV['COCOAPODS_DISABLE_STATS'] = 'true'

packages/webview_flutter/webview_flutter/example/ios/Runner.xcodeproj/project.pbxproj

@@ -3,7 +3,7 @@
 	archiveVersion = 1;
 	classes = {
 	};
-	objectVersion = 46;
+	objectVersion = 50;
 	objects = {
 
 /* Begin PBXBuildFile section */
@@ -274,7 +274,7 @@
 			isa = PBXProject;
 			attributes = {
 				DefaultBuildSystemTypeForWorkspace = Original;
-				LastUpgradeCheck = 1030;
+				LastUpgradeCheck = 1300;
 				ORGANIZATIONNAME = "The Flutter Authors";
 				TargetAttributes = {
 					68BDCAE823C3F7CB00D9C032 = {
@@ -552,7 +552,7 @@
 				GCC_WARN_UNINITIALIZED_AUTOS = YES_AGGRESSIVE;
 				GCC_WARN_UNUSED_FUNCTION = YES;
 				GCC_WARN_UNUSED_VARIABLE = YES;
-				IPHONEOS_DEPLOYMENT_TARGET = 9.0;
+				IPHONEOS_DEPLOYMENT_TARGET = 11.0;
 				MTL_ENABLE_DEBUG_INFO = YES;
 				ONLY_ACTIVE_ARCH = YES;
 				SDKROOT = iphoneos;
@@ -602,7 +602,7 @@
 				GCC_WARN_UNINITIALIZED_AUTOS = YES_AGGRESSIVE;
 				GCC_WARN_UNUSED_FUNCTION = YES;
 				GCC_WARN_UNUSED_VARIABLE = YES;
-				IPHONEOS_DEPLOYMENT_TARGET = 9.0;
+				IPHONEOS_DEPLOYMENT_TARGET = 11.0;
 				MTL_ENABLE_DEBUG_INFO = NO;
 				SDKROOT = iphoneos;
 				TARGETED_DEVICE_FAMILY = "1,2";

packages/webview_flutter/webview_flutter/example/ios/Runner.xcodeproj/xcshareddata/xcschemes/Runner.xcscheme

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <Scheme
-   LastUpgradeVersion = "1030"
+   LastUpgradeVersion = "1300"
    version = "1.3">
    <BuildAction
       parallelizeBuildables = "YES"

packages/webview_flutter/webview_flutter/example/ios/Runner/Info.plist

@@ -41,5 +41,7 @@
 	</array>
 	<key>UIViewControllerBasedStatusBarAppearance</key>
 	<false/>
+	<key>CADisableMinimumFrameDurationOnPhone</key>
+	<true/>
 </dict>
 </plist>

packages/webview_flutter/webview_flutter_wkwebview/ios/Classes/FWFInstanceManager.m

@@ -48,9 +48,16 @@ @interface FWFInstanceManager ()
 @property NSMapTable<NSObject *, NSNumber *> *identifiers;
 @property NSMapTable<NSNumber *, NSObject *> *weakInstances;
 @property NSMapTable<NSNumber *, NSObject *> *strongInstances;
+@property long nextIdentifier;
 @end
 
 @implementation FWFInstanceManager
+// Identifiers are locked to a specific range to avoid collisions with objects
+// created simultaneously by Dart.
+// Host uses identifiers >= 2^16 and Dart is expected to use values n where,
+// 0 <= n < 2^16.
+long const FWFMinHostCreatedIdentifier = 65536;
+
 - (instancetype)initWithDeallocCallback:(FWFOnDeallocCallback)callback {
   self = [self init];
   if (self) {
@@ -59,6 +66,7 @@ - (instancetype)initWithDeallocCallback:(FWFOnDeallocCallback)callback {
     _identifiers = [NSMapTable weakToStrongObjectsMapTable];
     _weakInstances = [NSMapTable strongToWeakObjectsMapTable];
     _strongInstances = [NSMapTable strongToStrongObjectsMapTable];
+    _nextIdentifier = FWFMinHostCreatedIdentifier;
   }
   return self;
 }
@@ -75,12 +83,7 @@ - (long)addHostCreatedInstance:(nonnull NSObject *)instance {
   NSParameterAssert(instance);
   long __block identifier = -1;
   dispatch_sync(_lockQueue, ^{
-    do {
-      // Identifiers are generated randomly to avoid collisions with objects
-      // created simultaneously by Flutter.
-      // Values are >= 2^16 and Flutter is expected to use values < 2^16.
-      identifier = arc4random_uniform(65536) + 65536;
-    } while ([self.weakInstances objectForKey:@(identifier)]);
+    identifier = self.nextIdentifier++;
     [self addInstance:instance withIdentifier:identifier];
   });
   return identifier;

packages/webview_flutter/webview_flutter_wkwebview/lib/src/common/instance_manager.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:math';
-
 import 'package:flutter/foundation.dart';
 
 /// An immutable object that can provide functional copies of themselves.
@@ -37,31 +35,36 @@ mixin Copyable {
 /// strong reference is added as a weak reference with the same identifier. This
 /// prevents a scenario where the weak referenced instance was released and then
 /// later returned by the host platform.
-// TODO(bparrishMines): Uncomment code with Finalizers and WeakReferences once
-// minimum dart version is bumped to 2.17.
 class InstanceManager {
   /// Constructs an [InstanceManager].
   InstanceManager({required void Function(int) onWeakReferenceRemoved}) {
     this.onWeakReferenceRemoved = (int identifier) {
       _weakInstances.remove(identifier);
       onWeakReferenceRemoved(identifier);
     };
+    _finalizer = Finalizer<int>(this.onWeakReferenceRemoved);
   }
 
+  // Identifiers are locked to a specific range to avoid collisions with objects
+  // created simultaneously by the host platform.
+  // Host uses identifiers >= 2^16 and Dart is expected to use values n where,
+  // 0 <= n < 2^16.
+  static const int _maxDartCreatedIdentifier = 65536;
+
   // Expando is used because it doesn't prevent its keys from becoming
   // inaccessible. This allows the manager to efficiently retrieve an identifier
   // of an instance without holding a strong reference to that instance.
   //
   // It also doesn't use `==` to search for identifiers, which would lead to an
   // infinite loop when comparing an object to its copy. (i.e. which was caused
-  // by calling instanceManager.getInstanceId() inside of `==` while this was a
+  // by calling instanceManager.getIdentifier() inside of `==` while this was a
   // HashMap).
   final Expando<int> _identifiers = Expando<int>();
-  final Map<int, Copyable> _weakInstances = <int, Copyable>{};
-  // final Map<int, WeakReference<Copyable>> _weakInstances =
-  //     <int, WeakReference<Copyable>>{};
+  final Map<int, WeakReference<Copyable>> _weakInstances =
+      <int, WeakReference<Copyable>>{};
   final Map<int, Copyable> _strongInstances = <int, Copyable>{};
-  // final Finalizer<int> _finalizer;
+  late final Finalizer<int> _finalizer;
+  int _nextIdentifier = 0;
 
   /// Called when a weak referenced instance is removed by [removeWeakReference]
   /// or becomes inaccessible.
@@ -75,10 +78,10 @@ class InstanceManager {
   /// Throws assertion error if the instance has already been added.
   ///
   /// Returns the randomly generated id of the [instance] added.
-  int addFlutterCreatedInstance(Copyable instance) {
+  int addDartCreatedInstance(Copyable instance) {
     assert(getIdentifier(instance) == null);
 
-    final int identifier = _generateNewIdentifier();
+    final int identifier = _nextUniqueIdentifier();
     _addInstanceWithIdentifier(instance, identifier);
     return identifier;
   }
@@ -98,7 +101,7 @@ class InstanceManager {
     }
 
     _identifiers[instance] = null;
-    //_finalizer.detach(instance);
+    _finalizer.detach(instance);
     onWeakReferenceRemoved(identifier);
 
     return identifier;
@@ -133,17 +136,15 @@ class InstanceManager {
     int identifier, {
     required bool returnedInstanceMayBeUsed,
   }) {
-    // final Copyable? weakInstance = _weakInstances[identifier]?.target;
-    final Copyable? weakInstance = _weakInstances[identifier];
+    final Copyable? weakInstance = _weakInstances[identifier]?.target;
 
     if (weakInstance == null) {
       final Copyable? strongInstance = _strongInstances[identifier];
       if (strongInstance != null && returnedInstanceMayBeUsed) {
         final Copyable copy = strongInstance.copy();
         _identifiers[copy] = identifier;
-        _weakInstances[identifier] = copy;
-        // _weakInstances[identifier] = WeakReference<Copyable>(copy);
-        // _finalizer.attach(copy, identifier, detach: copy);
+        _weakInstances[identifier] = WeakReference<Copyable>(copy);
+        _finalizer.attach(copy, identifier, detach: copy);
         return copy as T;
       }
       return strongInstance as T?;
@@ -175,9 +176,8 @@ class InstanceManager {
 
   void _addInstanceWithIdentifier(Copyable instance, int identifier) {
     _identifiers[instance] = identifier;
-    _weakInstances[identifier] = instance;
-    // _weakInstances[identifier] = WeakReference<Copyable>(instance);
-    // _finalizer.attach(instance, identifier, detach: instance);
+    _weakInstances[identifier] = WeakReference<Copyable>(instance);
+    _finalizer.attach(instance, identifier, detach: instance);
 
     final Copyable copy = instance.copy();
     _identifiers[copy] = identifier;
@@ -192,15 +192,10 @@ class InstanceManager {
         _strongInstances.containsKey(identifier);
   }
 
-  // Identifiers are generated randomly to avoid collisions with objects
-  // created simultaneously by the host platform.
-  int _generateNewIdentifier() {
-    late int identifier;
-    do {
-      // Values are less than 2^16 while the host platform is expected to use
-      // values greater than or equal to 2^16.
-      identifier = Random().nextInt(65536);
-    } while (containsIdentifier(identifier));
-    return identifier;
+  int _nextUniqueIdentifier() {
+    while (containsIdentifier(_nextIdentifier)) {
+      _nextIdentifier = (_nextIdentifier + 1) % _maxDartCreatedIdentifier;
+    }
+    return _nextIdentifier;
   }
 }

packages/webview_flutter/webview_flutter_wkwebview/lib/src/ui_kit/ui_kit_api_impls.dart

@@ -6,7 +6,6 @@ import 'dart:async';
 import 'dart:math';
 
 import 'package:flutter/painting.dart' show Color;
-import 'package:flutter/services.dart';
 
 import '../common/instance_manager.dart';
 import '../common/web_kit.pigeon.dart';
@@ -18,10 +17,9 @@ import 'ui_kit.dart';
 class UIScrollViewHostApiImpl extends UIScrollViewHostApi {
   /// Constructs a [UIScrollViewHostApiImpl].
   UIScrollViewHostApiImpl({
-    BinaryMessenger? binaryMessenger,
+    super.binaryMessenger,
     InstanceManager? instanceManager,
-  })  : instanceManager = instanceManager ?? NSObject.globalInstanceManager,
-        super(binaryMessenger: binaryMessenger);
+  })  : instanceManager = instanceManager ?? NSObject.globalInstanceManager;
 
   /// Maintains instances stored to communicate with Objective-C objects.
   final InstanceManager instanceManager;
@@ -31,7 +29,7 @@ class UIScrollViewHostApiImpl extends UIScrollViewHostApi {
     UIScrollView instance,
     WKWebView webView,
   ) {
-    final int instanceId = instanceManager.addFlutterCreatedInstance(instance);
+    final int instanceId = instanceManager.addDartCreatedInstance(instance);
     return createFromWebView(
       instanceId,
       instanceManager.getIdentifier(webView)!,
@@ -77,10 +75,9 @@ class UIScrollViewHostApiImpl extends UIScrollViewHostApi {
 class UIViewHostApiImpl extends UIViewHostApi {
   /// Constructs a [UIViewHostApiImpl].
   UIViewHostApiImpl({
-    BinaryMessenger? binaryMessenger,
+    super.binaryMessenger,
     InstanceManager? instanceManager,
-  })  : instanceManager = instanceManager ?? NSObject.globalInstanceManager,
-        super(binaryMessenger: binaryMessenger);
+  })  : instanceManager = instanceManager ?? NSObject.globalInstanceManager;
 
   /// Maintains instances stored to communicate with Objective-C objects.
   final InstanceManager instanceManager;