Invalid `Podfile` file: wrong number of arguments (0 for 1)

Question

I'm trying to build the ios app of a flutter project. when I run pod install, It fails with the error mentioned in the title and points to a line in my Podfile. That line is flutter_install_all_ios_pods File.dirname(File.realpath(__FILE__)).

I'm very new to IOS and this happens in all the projects I try to create. what am I doing wrong? Thanks in advance.

My Podfile is as follows,

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

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