[iOS] Fixes alert view block first responder

[zhongwuzw]

Summary

Fixes #23076 , the reason is blur() is managed by UIManager, UIManager maintains all operations and execute them each batchDidComplete, which means every time JS finish callback native , but Alert module would call directly, this mess up the order of method call, for example like below, even this.$input.blur() is called before Alert.alert(), but in native side, Alert.alert() is called before this.$input.blur().

        <TextInput style={{ borderWidth: 1 }} ref={$input => this.$input = $input} />
        <Button title="Show Alert" onPress={() => {
          // // `blur` works if using without `Alert`
          this.$input && this.$input.blur()
          // // `blur` is not working
          Alert.alert('show alert', 'desc', [
            { text: 'cancel', style: 'cancel' },
            { text: 'show', onPress: () => {
            }},
          ])
        }} />

Changelog

[iOS] [Fixed] - Fixes alert view block first responder

Test Plan

After fix, example like below, blur can works.

import * as React from 'react';
import { TextInput, View, Alert, Button } from 'react-native';

export default class App extends React.Component {
  render() {
    return (
      <View style={{ flex: 1, justifyContent: 'center' }}>
        <TextInput style={{ borderWidth: 1 }} ref={$input => this.$input = $input} />
        <Button title="Show Alert" onPress={() => {
          this.$input && this.$input.blur()
          Alert.alert('show alert', 'desc', [
            { text: 'cancel', style: 'cancel' },
            { text: 'show', onPress: () => { 
            }},
          ])
        }} />
      </View>
    );
  }
}

[facebook-github-bot]

@cpojer is landing this pull request. If you are a Facebook employee, you can view this diff on Phabricator.

[react-native-bot]

@zhongwuzw merged commit e4364fa into facebook:master.