[ios]fix ios 16 auto correction highlight showing on top left corner (#47279)

This PR hides the system highlights in iOS 16 (except when scribble is enabled). 

Note that auto correction highlight is still drawn by flutter, so it still works. 

I don't think we need to CP this, since it's iOS 16 only, and iOS 17 is already out. 

## Why not use system highlight? 

Unlike iOS 17, the iOS 16 system highlight only respect the width provided by `firstRectForRange`, but not the height. I have audited all sizing related APIs in UITextInput (doc [here](https://developer.apple.com/documentation/uikit/uitextinput#1653155)), specifically, `firstRect(for:)`, `caretRect(for:)` and `selectionRects(for:)`, and they all return the correct height. 

## About scribble
The initial implementation of `firstRectForRange` (that returns the first selection rect) was introduced for the scribble feature on iPad (code [here](1ae721c#diff-4c7b102c0690b8ec5e2212b079f5d69fe3f816c84e47ce94bc7bc89312f39e40R1487-R1505)). 

It turns out that a non-zero rect is required for scribble's advanced feature to work (e.g. inserting a space with a vertical bar). So we can't apply this fix for scribble. 

*List which issues are fixed by this PR. You must list at least one issue.*

Fixes flutter/flutter#136802

*If you had to change anything in the [flutter/tests] repo, include a link to the migration guide as per the [breaking change policy].*

[C++, Objective-C, Java style guides]: https://github.com/flutter/engine/blob/main/CONTRIBUTING.md#style

Author: hellohuanlin

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

@@ -1690,6 +1690,16 @@ - (CGRect)firstRectForRange:(UITextRange*)range {
     }
   }
 
+  // The iOS 16 system highlight does not repect the height returned by `firstRectForRange`
+  // API (unlike iOS 17). So we return CGRectZero to hide it (unless if scribble is enabled).
+  // To support scribble's advanced gestures (e.g. insert a space with a vertical bar),
+  // at least 1 character's width is required.
+  if (@available(iOS 17, *)) {
+    // No-op
+  } else if (![self isScribbleAvailable]) {
+    return CGRectZero;
+  }
+
   NSUInteger first = start;
   if (end < start) {
     first = end;

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

@@ -1558,19 +1558,19 @@ - (void)testUpdateFirstRectForRange {
                                   [inputView firstRectForRange:range]));
 }
 
-- (void)testFirstRectForRangeReturnsCorrectRectOnASingleLineLeftToRight {
+- (void)testFirstRectForRangeReturnsNoneZeroRectWhenScribbleIsEnabled {
   FlutterTextInputView* inputView = [[FlutterTextInputView alloc] initWithOwner:textInputPlugin];
   [inputView setTextInputState:@{@"text" : @"COMPOSING"}];
 
+  FlutterTextInputView* mockInputView = OCMPartialMock(inputView);
+  OCMStub([mockInputView isScribbleAvailable]).andReturn(YES);
+
   [inputView setSelectionRects:@[
     [FlutterTextSelectionRect selectionRectWithRect:CGRectMake(0, 0, 100, 100) position:0U],
     [FlutterTextSelectionRect selectionRectWithRect:CGRectMake(100, 0, 100, 100) position:1U],
     [FlutterTextSelectionRect selectionRectWithRect:CGRectMake(200, 0, 100, 100) position:2U],
     [FlutterTextSelectionRect selectionRectWithRect:CGRectMake(300, 0, 100, 100) position:3U],
   ]];
-  FlutterTextRange* singleRectRange = [FlutterTextRange rangeWithNSRange:NSMakeRange(1, 1)];
-  XCTAssertTrue(CGRectEqualToRect(CGRectMake(100, 0, 100, 100),
-                                  [inputView firstRectForRange:singleRectRange]));
 
   FlutterTextRange* multiRectRange = [FlutterTextRange rangeWithNSRange:NSMakeRange(1, 3)];
 
@@ -1581,6 +1581,34 @@ - (void)testFirstRectForRangeReturnsCorrectRectOnASingleLineLeftToRight {
     XCTAssertTrue(CGRectEqualToRect(CGRectMake(100, 0, 100, 100),
                                     [inputView firstRectForRange:multiRectRange]));
   }
+}
+
+- (void)testFirstRectForRangeReturnsCorrectRectOnASingleLineLeftToRight {
+  FlutterTextInputView* inputView = [[FlutterTextInputView alloc] initWithOwner:textInputPlugin];
+  [inputView setTextInputState:@{@"text" : @"COMPOSING"}];
+
+  [inputView setSelectionRects:@[
+    [FlutterTextSelectionRect selectionRectWithRect:CGRectMake(0, 0, 100, 100) position:0U],
+    [FlutterTextSelectionRect selectionRectWithRect:CGRectMake(100, 0, 100, 100) position:1U],
+    [FlutterTextSelectionRect selectionRectWithRect:CGRectMake(200, 0, 100, 100) position:2U],
+    [FlutterTextSelectionRect selectionRectWithRect:CGRectMake(300, 0, 100, 100) position:3U],
+  ]];
+  FlutterTextRange* singleRectRange = [FlutterTextRange rangeWithNSRange:NSMakeRange(1, 1)];
+  if (@available(iOS 17, *)) {
+    XCTAssertTrue(CGRectEqualToRect(CGRectMake(100, 0, 100, 100),
+                                    [inputView firstRectForRange:singleRectRange]));
+  } else {
+    XCTAssertTrue(CGRectEqualToRect(CGRectZero, [inputView firstRectForRange:singleRectRange]));
+  }
+
+  FlutterTextRange* multiRectRange = [FlutterTextRange rangeWithNSRange:NSMakeRange(1, 3)];
+
+  if (@available(iOS 17, *)) {
+    XCTAssertTrue(CGRectEqualToRect(CGRectMake(100, 0, 300, 100),
+                                    [inputView firstRectForRange:multiRectRange]));
+  } else {
+    XCTAssertTrue(CGRectEqualToRect(CGRectZero, [inputView firstRectForRange:multiRectRange]));
+  }
 
   [inputView setTextInputState:@{@"text" : @"COM"}];
   FlutterTextRange* rangeOutsideBounds = [FlutterTextRange rangeWithNSRange:NSMakeRange(3, 1)];
@@ -1598,16 +1626,19 @@ - (void)testFirstRectForRangeReturnsCorrectRectOnASingleLineRightToLeft {
     [FlutterTextSelectionRect selectionRectWithRect:CGRectMake(0, 0, 100, 100) position:3U],
   ]];
   FlutterTextRange* singleRectRange = [FlutterTextRange rangeWithNSRange:NSMakeRange(1, 1)];
-  XCTAssertTrue(CGRectEqualToRect(CGRectMake(200, 0, 100, 100),
-                                  [inputView firstRectForRange:singleRectRange]));
+  if (@available(iOS 17, *)) {
+    XCTAssertTrue(CGRectEqualToRect(CGRectMake(200, 0, 100, 100),
+                                    [inputView firstRectForRange:singleRectRange]));
+  } else {
+    XCTAssertTrue(CGRectEqualToRect(CGRectZero, [inputView firstRectForRange:singleRectRange]));
+  }
 
   FlutterTextRange* multiRectRange = [FlutterTextRange rangeWithNSRange:NSMakeRange(1, 3)];
   if (@available(iOS 17, *)) {
     XCTAssertTrue(CGRectEqualToRect(CGRectMake(0, 0, 300, 100),
                                     [inputView firstRectForRange:multiRectRange]));
   } else {
-    XCTAssertTrue(CGRectEqualToRect(CGRectMake(200, 0, 100, 100),
-                                    [inputView firstRectForRange:multiRectRange]));
+    XCTAssertTrue(CGRectEqualToRect(CGRectZero, [inputView firstRectForRange:multiRectRange]));
   }
 
   [inputView setTextInputState:@{@"text" : @"COM"}];
@@ -1630,17 +1661,20 @@ - (void)testFirstRectForRangeReturnsCorrectRectOnMultipleLinesLeftToRight {
     [FlutterTextSelectionRect selectionRectWithRect:CGRectMake(300, 100, 100, 100) position:7U],
   ]];
   FlutterTextRange* singleRectRange = [FlutterTextRange rangeWithNSRange:NSMakeRange(1, 1)];
-  XCTAssertTrue(CGRectEqualToRect(CGRectMake(100, 0, 100, 100),
-                                  [inputView firstRectForRange:singleRectRange]));
+  if (@available(iOS 17, *)) {
+    XCTAssertTrue(CGRectEqualToRect(CGRectMake(100, 0, 100, 100),
+                                    [inputView firstRectForRange:singleRectRange]));
+  } else {
+    XCTAssertTrue(CGRectEqualToRect(CGRectZero, [inputView firstRectForRange:singleRectRange]));
+  }
 
   FlutterTextRange* multiRectRange = [FlutterTextRange rangeWithNSRange:NSMakeRange(1, 4)];
 
   if (@available(iOS 17, *)) {
     XCTAssertTrue(CGRectEqualToRect(CGRectMake(100, 0, 300, 100),
                                     [inputView firstRectForRange:multiRectRange]));
   } else {
-    XCTAssertTrue(CGRectEqualToRect(CGRectMake(100, 0, 100, 100),
-                                    [inputView firstRectForRange:multiRectRange]));
+    XCTAssertTrue(CGRectEqualToRect(CGRectZero, [inputView firstRectForRange:multiRectRange]));
   }
 }
 
@@ -1659,16 +1693,19 @@ - (void)testFirstRectForRangeReturnsCorrectRectOnMultipleLinesRightToLeft {
     [FlutterTextSelectionRect selectionRectWithRect:CGRectMake(0, 100, 100, 100) position:7U],
   ]];
   FlutterTextRange* singleRectRange = [FlutterTextRange rangeWithNSRange:NSMakeRange(1, 1)];
-  XCTAssertTrue(CGRectEqualToRect(CGRectMake(200, 0, 100, 100),
-                                  [inputView firstRectForRange:singleRectRange]));
+  if (@available(iOS 17, *)) {
+    XCTAssertTrue(CGRectEqualToRect(CGRectMake(200, 0, 100, 100),
+                                    [inputView firstRectForRange:singleRectRange]));
+  } else {
+    XCTAssertTrue(CGRectEqualToRect(CGRectZero, [inputView firstRectForRange:singleRectRange]));
+  }
 
   FlutterTextRange* multiRectRange = [FlutterTextRange rangeWithNSRange:NSMakeRange(1, 4)];
   if (@available(iOS 17, *)) {
     XCTAssertTrue(CGRectEqualToRect(CGRectMake(0, 0, 300, 100),
                                     [inputView firstRectForRange:multiRectRange]));
   } else {
-    XCTAssertTrue(CGRectEqualToRect(CGRectMake(200, 0, 100, 100),
-                                    [inputView firstRectForRange:multiRectRange]));
+    XCTAssertTrue(CGRectEqualToRect(CGRectZero, [inputView firstRectForRange:multiRectRange]));
   }
 }
 
@@ -1691,8 +1728,7 @@ - (void)testFirstRectForRangeReturnsCorrectRectOnSingleLineWithVaryingMinYAndMax
     XCTAssertTrue(CGRectEqualToRect(CGRectMake(100, -10, 300, 120),
                                     [inputView firstRectForRange:multiRectRange]));
   } else {
-    XCTAssertTrue(CGRectEqualToRect(CGRectMake(100, 10, 100, 80),
-                                    [inputView firstRectForRange:multiRectRange]));
+    XCTAssertTrue(CGRectEqualToRect(CGRectZero, [inputView firstRectForRange:multiRectRange]));
   }
 }
 
@@ -1715,8 +1751,7 @@ - (void)testFirstRectForRangeReturnsCorrectRectOnSingleLineWithVaryingMinYAndMax
     XCTAssertTrue(CGRectEqualToRect(CGRectMake(0, -10, 300, 120),
                                     [inputView firstRectForRange:multiRectRange]));
   } else {
-    XCTAssertTrue(CGRectEqualToRect(CGRectMake(200, -10, 100, 120),
-                                    [inputView firstRectForRange:multiRectRange]));
+    XCTAssertTrue(CGRectEqualToRect(CGRectZero, [inputView firstRectForRange:multiRectRange]));
   }
 }
 
@@ -1739,8 +1774,7 @@ - (void)testFirstRectForRangeReturnsCorrectRectWithOverlappingRectsExceedingThre
     XCTAssertTrue(CGRectEqualToRect(CGRectMake(100, 0, 300, 100),
                                     [inputView firstRectForRange:multiRectRange]));
   } else {
-    XCTAssertTrue(CGRectEqualToRect(CGRectMake(100, 0, 100, 100),
-                                    [inputView firstRectForRange:multiRectRange]));
+    XCTAssertTrue(CGRectEqualToRect(CGRectZero, [inputView firstRectForRange:multiRectRange]));
   }
 }
 
@@ -1763,8 +1797,7 @@ - (void)testFirstRectForRangeReturnsCorrectRectWithOverlappingRectsExceedingThre
     XCTAssertTrue(CGRectEqualToRect(CGRectMake(0, 0, 300, 100),
                                     [inputView firstRectForRange:multiRectRange]));
   } else {
-    XCTAssertTrue(CGRectEqualToRect(CGRectMake(200, 0, 100, 100),
-                                    [inputView firstRectForRange:multiRectRange]));
+    XCTAssertTrue(CGRectEqualToRect(CGRectZero, [inputView firstRectForRange:multiRectRange]));
   }
 }
 
@@ -1787,8 +1820,7 @@ - (void)testFirstRectForRangeReturnsCorrectRectWithOverlappingRectsWithinThresho
     XCTAssertTrue(CGRectEqualToRect(CGRectMake(100, 0, 400, 140),
                                     [inputView firstRectForRange:multiRectRange]));
   } else {
-    XCTAssertTrue(CGRectEqualToRect(CGRectMake(100, 0, 100, 100),
-                                    [inputView firstRectForRange:multiRectRange]));
+    XCTAssertTrue(CGRectEqualToRect(CGRectZero, [inputView firstRectForRange:multiRectRange]));
   }
 }
 
@@ -1811,8 +1843,7 @@ - (void)testFirstRectForRangeReturnsCorrectRectWithOverlappingRectsWithinThresho
     XCTAssertTrue(CGRectEqualToRect(CGRectMake(0, 0, 400, 140),
                                     [inputView firstRectForRange:multiRectRange]));
   } else {
-    XCTAssertTrue(CGRectEqualToRect(CGRectMake(300, 0, 100, 100),
-                                    [inputView firstRectForRange:multiRectRange]));
+    XCTAssertTrue(CGRectEqualToRect(CGRectZero, [inputView firstRectForRange:multiRectRange]));
   }
 }