[iOS text input] Use the correct coordinate space for firstRectForRange

shell/platform/darwin/common/framework/Source/FlutterCodecs.mm

@@ -66,17 +66,18 @@ - (NSData*)encode:(id)message {
     return nil;
   }
   NSData* encoding;
+  NSError* error;
   if ([message isKindOfClass:[NSArray class]] || [message isKindOfClass:[NSDictionary class]]) {
-    encoding = [NSJSONSerialization dataWithJSONObject:message options:0 error:nil];
+    encoding = [NSJSONSerialization dataWithJSONObject:message options:0 error:&error];
   } else {
     // NSJSONSerialization does not support top-level simple values.
     // We encode as singleton array, then extract the relevant bytes.
-    encoding = [NSJSONSerialization dataWithJSONObject:@[ message ] options:0 error:nil];
+    encoding = [NSJSONSerialization dataWithJSONObject:@[ message ] options:0 error:&error];
     if (encoding) {
       encoding = [encoding subdataWithRange:NSMakeRange(1, encoding.length - 2)];
     }
   }
-  NSAssert(encoding, @"Invalid JSON message, encoding failed");
+  NSAssert(encoding, @"Invalid JSON message, encoding failed: %@", error);
   return encoding;
 }
 

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

@@ -707,6 +707,7 @@ - (void)forwardInvocation:(NSInvocation*)anInvocation {
 @interface FlutterTextInputPlugin ()
 @property(nonatomic, readonly) fml::WeakPtr<FlutterTextInputPlugin> weakPtr;
 @property(nonatomic, readonly) id<FlutterTextInputDelegate> textInputDelegate;
+@property(nonatomic, readonly) UIView* hostView;
 @end
 
 @interface FlutterTextInputView ()
@@ -1602,7 +1603,10 @@ - (CGRect)firstRectForRange:(UITextRange*)range {
       _cachedFirstRect = [self localRectFromFrameworkTransform:rect];
     }
 
-    return _cachedFirstRect;
+    UIView* hostView = _textInputPlugin.get().hostView;
+    NSAssert(hostView == nil || [self isDescendantOfView:hostView], @"%@ is not a descendant of %@",
+             self, hostView);
+    return hostView ? [hostView convertRect:_cachedFirstRect toView:self] : _cachedFirstRect;
   }
 
   if (_scribbleInteractionStatus == FlutterScribbleInteractionStatusNone &&

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

@@ -1217,7 +1217,11 @@ - (void)testInputViewsDoNotHaveUITextInteractions {
 #pragma mark - UITextInput methods - Tests
 
 - (void)testUpdateFirstRectForRange {
-  FlutterTextInputView* inputView = [[FlutterTextInputView alloc] initWithOwner:textInputPlugin];
+  [self setClientId:123 configuration:self.mutableTemplateCopy];
+
+  FlutterTextInputView* inputView = textInputPlugin.activeView;
+  textInputPlugin.viewController.view.frame = CGRectMake(0, 0, 0, 0);
+
   [inputView
       setTextInputState:@{@"text" : @"COMPOSING", @"composingBase" : @1, @"composingExtent" : @3}];
 
@@ -1272,6 +1276,16 @@ - (void)testUpdateFirstRectForRange {
   [inputView setMarkedRect:testRect];
   XCTAssertTrue(
       CGRectEqualToRect(CGRectMake(-306, 3, 300, 300), [inputView firstRectForRange:range]));
+
+  NSAssert(inputView.superview, @"inputView is not in the view hierarchy!");
+  const CGPoint offset = CGPointMake(113, 119);
+  CGRect currentFrame = inputView.frame;
+  currentFrame.origin = offset;
+  inputView.frame = currentFrame;
+  // Moving the input view within the FlutterView shouldn't affect the coordinates,
+  // since the framework sends us global coordinates.
+  XCTAssertTrue(CGRectEqualToRect(CGRectMake(-306 - 113, 3 - 119, 300, 300),
+                                  [inputView firstRectForRange:range]));
 }
 
 - (void)testFirstRectForRangeReturnsCorrectSelectionRect {