From 67219ec72af60d48aeb041d7f0491fc4b1b180ae Mon Sep 17 00:00:00 2001
From: Jason Zheng <jasonqzheng@meta.com>
Date: Tue, 27 Oct 2026 23:24:27 -0700
Subject: [PATCH 1/2] Add auto-expanding multiline TextInput example to
 RNTester (#59416)

Summary:

Add a new RNTester example in TextInputSharedExamples to reproduce iOS and Android issues with auto-expanding multiline text fields. There is already an existing example, but an empty, uncontrolled variant is needed to reproduce certain issues. An existing iOS-only auto-expanding example is removed as well since it duplicates functionality.

Changelog: [Internal]

Differential Revision: D127048669
---
 .../examples/TextInput/TextInputExample.ios.js  | 17 -----------------
 .../TextInput/TextInputSharedExamples.js        | 14 ++++++++++++++
 2 files changed, 14 insertions(+), 17 deletions(-)

diff --git a/packages/rn-tester/js/examples/TextInput/TextInputExample.ios.js b/packages/rn-tester/js/examples/TextInput/TextInputExample.ios.js
index a6bcda4ec182..b768aff875ed 100644
--- a/packages/rn-tester/js/examples/TextInput/TextInputExample.ios.js
+++ b/packages/rn-tester/js/examples/TextInput/TextInputExample.ios.js
@@ -778,23 +778,6 @@ const textInputExamples: Array<RNTesterModuleExample> = [
       );
     },
   },
-  {
-    title: 'Auto-expanding',
-    render: function (): React.Node {
-      return (
-        <View>
-          <ExampleTextInput
-            placeholder="height increases with content"
-            defaultValue="React Native enables you to build world-class application experiences on native platforms using a consistent developer experience based on JavaScript and React. The focus of React Native is on developer efficiency across all the platforms you care about - learn once, write anywhere. Facebook uses React Native in multiple production apps and will continue investing in React Native."
-            multiline={true}
-            enablesReturnKeyAutomatically={true}
-            returnKeyType="go"
-            style={[styles.multiline, styles.multilineExpandable]}
-          />
-        </View>
-      );
-    },
-  },
   {
     title: 'TextInput maxLength',
     render: function (): React.Node {
diff --git a/packages/rn-tester/js/examples/TextInput/TextInputSharedExamples.js b/packages/rn-tester/js/examples/TextInput/TextInputSharedExamples.js
index 795ea66911ea..60df3a252499 100644
--- a/packages/rn-tester/js/examples/TextInput/TextInputSharedExamples.js
+++ b/packages/rn-tester/js/examples/TextInput/TextInputSharedExamples.js
@@ -1192,6 +1192,20 @@ module.exports = [
       );
     },
   },
+  {
+    title: 'Auto-expanding (uncontrolled)',
+    render: function (): React.Node {
+      return (
+        <View>
+          <ExampleTextInput
+            placeholder="height should grow up to 10 lines"
+            multiline={true}
+            numberOfLines={10}
+          />
+        </View>
+      );
+    },
+  },
   {
     title: 'Drag and drop',
     render: function (): React.Node {

From ea42d2b0b8c66b773fa3ec3fb2e2adb1965bf832 Mon Sep 17 00:00:00 2001
From: Jason Zheng <jasonqzheng@meta.com>
Date: Tue, 27 Oct 2026 23:24:27 -0700
Subject: [PATCH 2/2] Fix uncontrolled multiline TextInput not expanding on iOS
 (#59417)

Summary:

Fixes an issue where on iOS, multiline expanding TextInputs do not expand if the input starts off as empty and uncontrolled.

### Root Cause

When a multiline TextInput on iOS is provided a `value` and `onChange()` prop, as shown in the [React Native docs](https://reactnative.dev/docs/textinput), the input grows as expected. However, uncontrolled inputs do not grow past the first initial line.

On mount, `BaseTextInputShadowNode::updateStateIfNeeded()` writes state only if the text changes, so the first state write is skipped for empty, uncontrolled inputs. As a result, `TextAttributes` keeps the default `fontSizeMultiplier = NaN` which is carried over since iOS copies the previous state for subsequent keystrokes. During measurement, `attributedStringBoxToMeasure()` sees that the current multiplier doesn't match the stored multiplier of NaN and falls back to `props.text` which is empty for uncontrolled inputs. This causes the input to stay one-line tall.

### This PR

Modify `BaseTextInputShadowNode::updateStateIfNeeded()` to update the state if base text attributes differ. On mount, the default font multiplier of NaN now differs from the real multiplier, so a state update occurs and the text field grows normally.

Changelog: [iOS][Fixed] - Fix multiline TextInput not growing with its content when uncontrolled and initially empty

Reviewed By: vzaidman

Differential Revision: D127048714
---
 .../renderer/components/textinput/BaseTextInputShadowNode.h   | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/packages/react-native/ReactCommon/react/renderer/components/textinput/BaseTextInputShadowNode.h b/packages/react-native/ReactCommon/react/renderer/components/textinput/BaseTextInputShadowNode.h
index 42cf11b0695f..fe0caaec6097 100644
--- a/packages/react-native/ReactCommon/react/renderer/components/textinput/BaseTextInputShadowNode.h
+++ b/packages/react-native/ReactCommon/react/renderer/components/textinput/BaseTextInputShadowNode.h
@@ -157,7 +157,9 @@ class BaseTextInputShadowNode
     const auto &stateData = BaseShadowNode::getStateData();
     const auto &reactTreeAttributedString = getAttributedString(layoutContext);
 
-    if (stateData.reactTreeAttributedString.isContentEqual(reactTreeAttributedString)) {
+    if (stateData.reactTreeAttributedString.isContentEqual(reactTreeAttributedString) &&
+        stateData.reactTreeAttributedString.getBaseTextAttributes() ==
+            reactTreeAttributedString.getBaseTextAttributes()) {
       return;
     }