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Fabrizio BertoglioandFacebook GitHub Bot
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Summary: ### Please re-state the problem that we are trying to solve in this issue. Multiline TextInput with a fixed height will scroll to the bottom of the screen when prepending new lines to the text. ### What is the root cause of that problem? The issue is caused by iOS UITextView: - The cursor moves to the end of the text when prepending new lines. - Moving the cursor to the end of the text triggers the scroll to the bottom. The behavior was reproduced on an iOS App (without react-native). The example included below implements a Component RCTUITextView based on UITextView, which modifies the UITextView attributedText with the textViewDidChange callback (source code available in this [comment](https://github.com/Expensify/App/issues/19507#issuecomment-1595730348)). Adding a new line on top of the UITextView on iOS results in: Issue 1) The cursor moves to the end of TextInput text Issue 2) The TextInput scrolls to the bottom <details><summary>Reproducing the issue on an iOS App without react-native</summary> <p> <video src="https://user-images.githubusercontent.com/24992535/246601549-99f480f3-ce80-4678-9378-f71c8aa67e17.mp4" width="900" /> </p> </details> Issue 1) is already fixed in react-native, which restores the previous cursor position (on Fabric with [_setAttributedString](https://github.com/fabriziobertoglio1987/react-native/blob/71e7bbbc2cf21abacf7009e300f5bba737e20d17/packages/react-native/React/Fabric/Mounting/ComponentViews/TextInput/RCTTextInputComponentView.mm#L600-L610)) after changing the text. Issue 2) needs to be fixed in react-native. ### What changes do you think we should make in order to solve the problem? Setting the correct TextInput scroll position after re-setting the cursor. ## Changelog: [IOS] [FIXED] - Fix Multiline TextInput with a fixed height scrolls to the bottom when changing AttributedText Pull Request resolved: https://github.com/facebook/react-native/pull/38679 Test Plan: Fabric (reproduces on controlled/not controlled TextInput example): | Before | After | | ----------- | ----------- | | <video src="https://github.com/facebook/react-native/assets/24992535/e06b31fe-407d-4897-b608-73e0cc0f224a" width="350" /> | <video src="https://github.com/facebook/react-native/assets/24992535/fa2eaa31-c616-43c5-9596-f84e7b70d80a" width="350" /> | Paper (reproduces only on controlled TextInput example): ```javascript function TextInputExample() { const [text, setText] = React.useState(''); return ( <View style={{marginTop: 200}}> <TextInput style={{height: 50, backgroundColor: 'white'}} multiline={true} value={text} onChangeText={text => { setText(text); }} /> </View> ); } ``` | Before | After | | ----------- | ----------- | | <video src="https://github.com/facebook/react-native/assets/24992535/6cb1f2de-717e-4dce-be0a-644f6a051c08" width="350" /> | <video src="https://github.com/facebook/react-native/assets/24992535/dee6edb6-76c6-48b0-b78f-99626235d30e" width="350" /> | Reviewed By: sammy-SC, cipolleschi Differential Revision: D48674090 Pulled By: NickGerleman fbshipit-source-id: 349e7b0910e314ec94b45b68c38571fed41ef117