[CP] Workaround iOS text input crash for emoji+Korean text

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

@@ -7,6 +7,8 @@
 #import <Foundation/Foundation.h>
 #import <UIKit/UIKit.h>
 
+#include "unicode/uchar.h"
+
 #include "flutter/fml/logging.h"
 #include "flutter/fml/platform/darwin/string_range_sanitization.h"
 
@@ -71,6 +73,19 @@
 
 #pragma mark - Static Functions
 
+// Determine if the character at `range` of `text` is an emoji.
+static BOOL IsEmoji(NSString* text, NSRange charRange) {
+  UChar32 codePoint;
+  BOOL gotCodePoint = [text getBytes:&codePoint
+                           maxLength:sizeof(codePoint)
+                          usedLength:NULL
+                            encoding:NSUTF32StringEncoding
+                             options:kNilOptions
+                               range:charRange
+                      remainingRange:NULL];
+  return gotCodePoint && u_hasBinaryProperty(codePoint, UCHAR_EMOJI);
+}
+
 // "TextInputType.none" is a made-up input type that's typically
 // used when there's an in-app virtual keyboard. If
 // "TextInputType.none" is specified, disable the system
@@ -713,6 +728,10 @@ @interface FlutterTextInputView ()
 @property(nonatomic, assign) CGRect markedRect;
 @property(nonatomic) BOOL isVisibleToAutofill;
 @property(nonatomic, assign) BOOL accessibilityEnabled;
+// The composed character that is temporarily removed by the keyboard API.
+// This is cleared at the start of each keyboard interaction. (Enter a character, delete a character
+// etc)
+@property(nonatomic, copy) NSString* temporarilyDeletedComposedCharacter;
 
 - (void)setEditableTransform:(NSArray*)matrix;
 @end
@@ -899,6 +918,8 @@ - (void)dealloc {
   [_markedTextStyle release];
   [_textContentType release];
   [_textInteraction release];
+  [_temporarilyDeletedComposedCharacter release];
+  _temporarilyDeletedComposedCharacter = nil;
   [super dealloc];
 }
 
@@ -1243,6 +1264,10 @@ - (void)replaceRange:(UITextRange*)range withText:(NSString*)text {
 }
 
 - (BOOL)shouldChangeTextInRange:(UITextRange*)range replacementText:(NSString*)text {
+  // `temporarilyDeletedComposedCharacter` should only be used during a single text change session.
+  // So it needs to be cleared at the start of each text editting session.
+  self.temporarilyDeletedComposedCharacter = nil;
+
   if (self.returnKeyType == UIReturnKeyDefault && [text isEqualToString:@"\n"]) {
     [self.textInputDelegate flutterTextInputView:self
                                    performAction:FlutterTextInputActionNewline
@@ -1830,6 +1855,15 @@ - (BOOL)hasText {
 }
 
 - (void)insertText:(NSString*)text {
+  if (self.temporarilyDeletedComposedCharacter.length > 0 && text.length == 1 && !text.UTF8String &&
+      [text characterAtIndex:0] == [self.temporarilyDeletedComposedCharacter characterAtIndex:0]) {
+    // Workaround for https://github.com/flutter/flutter/issues/111494
+    // TODO(cyanglaz): revert this workaround if when flutter supports a minimum iOS version which
+    // this bug is fixed by Apple.
+    text = self.temporarilyDeletedComposedCharacter;
+    self.temporarilyDeletedComposedCharacter = nil;
+  }
+
   NSMutableArray<FlutterTextSelectionRect*>* copiedRects =
       [[NSMutableArray alloc] initWithCapacity:[_selectionRects count]];
   NSAssert([_selectedTextRange.start isKindOfClass:[FlutterTextPosition class]],
@@ -1896,12 +1930,29 @@ - (void)deleteBackward {
     NSRange oldRange = ((FlutterTextRange*)oldSelectedRange).range;
     if (oldRange.location > 0) {
       NSRange newRange = NSMakeRange(oldRange.location - 1, 1);
+
+      // We should check if the last character is a part of emoji.
+      // If so, we must delete the entire emoji to prevent the text from being malformed.
+      NSRange charRange = fml::RangeForCharacterAtIndex(self.text, oldRange.location - 1);
+      if (IsEmoji(self.text, charRange)) {
+        newRange = NSMakeRange(charRange.location, oldRange.location - charRange.location);
+      }
+
       _selectedTextRange = [[FlutterTextRange rangeWithNSRange:newRange] copy];
       [oldSelectedRange release];
     }
   }
 
   if (!_selectedTextRange.isEmpty) {
+    // Cache the last deleted emoji to use for an iOS bug where the next
+    // insertion corrupts the emoji characters.
+    // See: https://github.com/flutter/flutter/issues/111494#issuecomment-1248441346
+    if (IsEmoji(self.text, _selectedTextRange.range)) {
+      NSString* deletedText = [self.text substringWithRange:_selectedTextRange.range];
+      NSRange deleteFirstCharacterRange = fml::RangeForCharacterAtIndex(deletedText, 0);
+      self.temporarilyDeletedComposedCharacter =
+          [deletedText substringWithRange:deleteFirstCharacterRange];
+    }
     [self replaceRange:_selectedTextRange withText:@""];
   }
 }

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

@@ -406,6 +406,100 @@ - (void)testStandardEditActions {
   XCTAssertEqualObjects(substring, @"bbbbaaaabbbbaaaa");
 }
 
+- (void)testDeletingBackward {
+  NSDictionary* config = self.mutableTemplateCopy;
+  [self setClientId:123 configuration:config];
+  NSArray<FlutterTextInputView*>* inputFields = self.installedInputViews;
+  FlutterTextInputView* inputView = inputFields[0];
+
+  [inputView insertText:@"ឹ😀 text 🥰👨‍👩‍👧‍👦🇺🇳ดี "];
+  [inputView deleteBackward];
+  [inputView deleteBackward];
+
+  // Thai vowel is removed.
+  XCTAssertEqualObjects(inputView.text, @"ឹ😀 text 🥰👨‍👩‍👧‍👦🇺🇳ด");
+  [inputView deleteBackward];
+  XCTAssertEqualObjects(inputView.text, @"ឹ😀 text 🥰👨‍👩‍👧‍👦🇺🇳");
+  [inputView deleteBackward];
+  XCTAssertEqualObjects(inputView.text, @"ឹ😀 text 🥰👨‍👩‍👧‍👦");
+  [inputView deleteBackward];
+  XCTAssertEqualObjects(inputView.text, @"ឹ😀 text 🥰");
+  [inputView deleteBackward];
+
+  XCTAssertEqualObjects(inputView.text, @"ឹ😀 text ");
+  [inputView deleteBackward];
+  [inputView deleteBackward];
+  [inputView deleteBackward];
+  [inputView deleteBackward];
+  [inputView deleteBackward];
+  [inputView deleteBackward];
+
+  XCTAssertEqualObjects(inputView.text, @"ឹ😀");
+  [inputView deleteBackward];
+  XCTAssertEqualObjects(inputView.text, @"ឹ");
+  [inputView deleteBackward];
+  XCTAssertEqualObjects(inputView.text, @"");
+}
+
+// This tests the workaround to fix an iOS 16 bug
+// See: https://github.com/flutter/flutter/issues/111494
+- (void)testSystemOnlyAddingPartialComposedCharacter {
+  NSDictionary* config = self.mutableTemplateCopy;
+  [self setClientId:123 configuration:config];
+  NSArray<FlutterTextInputView*>* inputFields = self.installedInputViews;
+  FlutterTextInputView* inputView = inputFields[0];
+
+  [inputView insertText:@"👨‍👩‍👧‍👦"];
+  [inputView deleteBackward];
+
+  // Insert the first unichar in the emoji.
+  [inputView insertText:[@"👨‍👩‍👧‍👦" substringWithRange:NSMakeRange(0, 1)]];
+  [inputView insertText:@"아"];
+
+  XCTAssertEqualObjects(inputView.text, @"👨‍👩‍👧‍👦아");
+
+  // Deleting 아.
+  [inputView deleteBackward];
+  // 👨‍👩‍👧‍👦 should be the current string.
+
+  [inputView insertText:@"😀"];
+  [inputView deleteBackward];
+  // Insert the first unichar in the emoji.
+  [inputView insertText:[@"😀" substringWithRange:NSMakeRange(0, 1)]];
+  [inputView insertText:@"아"];
+  XCTAssertEqualObjects(inputView.text, @"👨‍👩‍👧‍👦😀아");
+
+  // Deleting 아.
+  [inputView deleteBackward];
+  // 👨‍👩‍👧‍👦😀 should be the current string.
+
+  [inputView deleteBackward];
+  // Insert the first unichar in the emoji.
+  [inputView insertText:[@"😀" substringWithRange:NSMakeRange(0, 1)]];
+  [inputView insertText:@"아"];
+
+  XCTAssertEqualObjects(inputView.text, @"👨‍👩‍👧‍👦😀아");
+}
+
+- (void)testCachedComposedCharacterClearedAtKeyboardInteraction {
+  NSDictionary* config = self.mutableTemplateCopy;
+  [self setClientId:123 configuration:config];
+  NSArray<FlutterTextInputView*>* inputFields = self.installedInputViews;
+  FlutterTextInputView* inputView = inputFields[0];
+
+  [inputView insertText:@"👨‍👩‍👧‍👦"];
+  [inputView deleteBackward];
+  [inputView shouldChangeTextInRange:OCMClassMock([UITextRange class]) replacementText:@""];
+
+  // Insert the first unichar in the emoji.
+  NSString* brokenEmoji = [@"👨‍👩‍👧‍👦" substringWithRange:NSMakeRange(0, 1)];
+  [inputView insertText:brokenEmoji];
+  [inputView insertText:@"아"];
+
+  NSString* finalText = [NSString stringWithFormat:@"%@아", brokenEmoji];
+  XCTAssertEqualObjects(inputView.text, finalText);
+}
+
 - (void)testPastingNonTextDisallowed {
   NSDictionary* config = self.mutableTemplateCopy;
   [self setClientId:123 configuration:config];

testing/ios/IosUnitTests/IosUnitTests.xcodeproj/xcshareddata/xcschemes/IosUnitTests.xcscheme

@@ -78,6 +78,12 @@
             ReferencedContainer = "container:IosUnitTests.xcodeproj">
          </BuildableReference>
       </BuildableProductRunnable>
+      <CommandLineArguments>
+         <CommandLineArgument
+            argument = "--icu-data-file-path=Frameworks/Flutter.framework/icudtl.dat"
+            isEnabled = "YES">
+         </CommandLineArgument>
+      </CommandLineArguments>
    </LaunchAction>
    <ProfileAction
       buildConfiguration = "Release"