Answers for "Flutter.h' file not found"

fatal error: 'flutter/flutter.h' file not found #import <flutter/flutter.h>

Swift, Flutter/Dart
Try these commands:

flutter clean
rm -rf ios/Podfile.lock ios/Pods/
flutter run

// This worked for me most of the time. I believe the consequence 
// of a Podfile older than Podfile.lock is that pod install isn't 
// executed as part of flutter run. The above fixes that.

// Another thing to try if the latter fails, check all the packages. One of them might not support Flutter 2 yet 
// or vice versa.For this go to your files and see if an of the imports have warnings.
// Tricky error lots of ways to solve the error but more info would help.

fatal error: 'Flutter/Flutter.h' file not found site:stackoverflow.com

/// Replace your pod file with this one
platform :ios, '12.0'

ENV['COCOAPODS_DISABLE_STATS'] = 'true'

project 'Runner', {
  'Debug' => :debug,
  'Profile' => :release,
  'Release' => :release,
}

def flutter_root
  generated_xcode_build_settings_path = File.expand_path(File.join('..', 'Flutter', 'Generated.xcconfig'), __FILE__)
  unless File.exist?(generated_xcode_build_settings_path)
    raise "#{generated_xcode_build_settings_path} must exist. If you're running pod install manually, make sure flutter pub get is executed first"
  end

  File.foreach(generated_xcode_build_settings_path) do |line|
    matches = line.match(/FLUTTER_ROOT\=(.*)/)
    return matches[1].strip if matches
  end
  raise "FLUTTER_ROOT not found in #{generated_xcode_build_settings_path}. Try deleting Generated.xcconfig, then run flutter pub get"
end

require File.expand_path(File.join('packages', 'flutter_tools', 'bin', 'podhelper'), flutter_root)

flutter_ios_podfile_setup

def flutter_install_ios_plugin_pods(ios_application_path = nil)
  ios_application_path ||= File.dirname(defined_in_file.realpath) if self.respond_to?(:defined_in_file)
  raise 'Could not find iOS application path' unless ios_application_path

  symlink_dir = File.expand_path('.symlinks', ios_application_path)
  system('rm', '-rf', symlink_dir) # Avoid the complication of dependencies like FileUtils.

  symlink_plugins_dir = File.expand_path('plugins', symlink_dir)
  system('mkdir', '-p', symlink_plugins_dir)

  plugins_file = File.join(ios_application_path, '..', '.flutter-plugins-dependencies')
  plugin_pods = flutter_parse_plugins_file(plugins_file)
  plugin_pods.each do |plugin_hash|
    plugin_name = plugin_hash['name']
    plugin_path = plugin_hash['path']
    if (plugin_name && plugin_path)
      symlink = File.join(symlink_plugins_dir, plugin_name)
      File.symlink(plugin_path, symlink)

      if plugin_name == 'flutter_ffmpeg'
          pod 'flutter_ffmpeg/full-lts', :path => File.join('.symlinks', 'plugins', plugin_name, 'ios')
      else
          pod plugin_name, :path => File.join('.symlinks', 'plugins', plugin_name, 'ios')
      end
    end
  end
end

target 'Runner' do
  use_frameworks!
  use_modular_headers!

  flutter_install_all_ios_pods File.dirname(File.realpath(__FILE__))
end

post_install do |installer|
  installer.pods_project.targets.each do |target|
    flutter_additional_ios_build_settings(target)
  end
end

/// And Run
flutter pub get
cd ios
pod install

/// EDIT
/// if it doesn't work then

flutter pod update
flutter clean
flutter run
@Credit Latalus