[iOS] Fixes crash of TextInputView when Flutter deallocated (#25070)

shell/platform/darwin/ios/framework/Source/FlutterTextInputPlugin.mm

@@ -1234,6 +1234,30 @@ static FlutterAutofillType autofillTypeOf(NSDictionary* configuration) {
 
 @end
 
+@interface FlutterTextInputPlugin ()
+- (void)enableActiveViewAccessibility;
+@end
+
+@interface FlutterTimerProxy : NSObject
+@property(nonatomic, assign) FlutterTextInputPlugin* target;
+@end
+
+@implementation FlutterTimerProxy
+
++ (instancetype)proxyWithTarget:(FlutterTextInputPlugin*)target {
+  FlutterTimerProxy* proxy = [[self new] autorelease];
+  if (proxy) {
+    proxy.target = target;
+  }
+  return proxy;
+}
+
+- (void)enableActiveViewAccessibility {
+  [self.target enableActiveViewAccessibility];
+}
+
+@end
+
 @interface FlutterTextInputPlugin ()
 @property(nonatomic, strong) FlutterTextInputView* reusableInputView;
 
@@ -1266,6 +1290,7 @@ static FlutterAutofillType autofillTypeOf(NSDictionary* configuration) {
 
 - (void)dealloc {
   [self hideTextInput];
+  _activeView.textInputDelegate = nil;
   [_reusableInputView release];
   [_activeView release];
   [_inputHider release];
@@ -1344,15 +1369,15 @@ static FlutterAutofillType autofillTypeOf(NSDictionary* configuration) {
   if (!_enableFlutterTextInputViewAccessibilityTimer) {
     _enableFlutterTextInputViewAccessibilityTimer =
         [[NSTimer scheduledTimerWithTimeInterval:kUITextInputAccessibilityEnablingDelaySeconds
-                                          target:self
-                                        selector:@selector(enableActiveViewAccessibility:)
+                                          target:[FlutterTimerProxy proxyWithTarget:self]
+                                        selector:@selector(enableActiveViewAccessibility)
                                         userInfo:nil
                                          repeats:NO] retain];
   }
   [_activeView becomeFirstResponder];
 }
 
-- (void)enableActiveViewAccessibility:(NSTimer*)time {
+- (void)enableActiveViewAccessibility {
   if (_activeView.isFirstResponder) {
     _activeView.accessibilityEnabled = YES;
   }

shell/platform/darwin/ios/framework/Source/FlutterTextInputPluginTest.m

@@ -240,6 +240,18 @@ FLUTTER_ASSERT_ARC
   XCTAssert([[passwordView.textField description] containsString:@"TextField"]);
 }
 
+- (void)testInputViewCrash {
+  FlutterTextInputView* activeView = nil;
+  @autoreleasepool {
+    FlutterTextInputPlugin* inputPlugin = [FlutterTextInputPlugin new];
+    activeView = inputPlugin.activeView;
+    FlutterEngine* flutterEngine = [[FlutterEngine alloc] init];
+    activeView.textInputDelegate = (id<FlutterTextInputDelegate>)flutterEngine;
+  }
+  XCTAssert(!activeView.textInputDelegate);
+  [activeView updateEditingState];
+}
+
 - (void)ensureOnlyActiveViewCanBecomeFirstResponder {
   for (FlutterTextInputView* inputView in self.installedInputViews) {
     XCTAssertEqual(inputView.canBecomeFirstResponder, inputView == textInputPlugin.activeView);