Repository: flutter
Issue: `pod init` does not work on Xcode projects created using Xcode 16 beta
Labels: a: existing-apps,P2,team-ios,triaged-ios

# Problem

CocoaPods's `pod init` command is broken on projects created using Xcode 16 beta: https://github.com/CocoaPods/CocoaPods/issues/12456

# Work

* [x] If Xcode 16 ships before CocoaPods fixes this issue, add known workarounds to our [add-to-add project setup instructions](https://github.com/flutter/website/blob/a341c79f45ddd3a55542719c1ae0c114add5eef6/src/_includes/docs/add-to-app/ios-project/embed-cocoapods.md?plain=1#L55) (ex: create your iOS project using Xcode 15)
* [x] https://github.com/flutter/flutter/issues/156733
* [ ] When CocoaPods fixes this issue, update the minimum required CocoaPods version in `flutter doctor` and docs

# Steps to reproduce

1. Create a new SwiftUI project using Xcode 16 beta 5
2. Run `pod init` in the created directory

You'll get the following error:

<details>
<summary>Error output...</summary>

````
$ pod init

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### Command

```
/Users/loicsharma/homebrew/lib/ruby/gems/3.3.0/bin/pod init
```

### Report

* What did you do?

* What did you expect to happen?

* What happened instead?


### Stack

```
   CocoaPods : 1.15.2
        Ruby : ruby 3.3.1 (2024-04-23 revision c56cd86388) [arm64-darwin23]
    RubyGems : 3.5.9
        Host : macOS 14.6.1 (23G93)
       Xcode : 16.0 (16A5221g)
         Git : git version 2.46.0.76.ge559c4bf1a-goog
Ruby lib dir : /Users/loicsharma/homebrew/Cellar/ruby/3.3.1/lib
Repositories : trunk - CDN - https://cdn.cocoapods.org/
```

### Plugins

```
cocoapods-deintegrate : 1.0.5
cocoapods-plugins     : 1.0.0
cocoapods-search      : 1.0.1
cocoapods-trunk       : 1.6.0
cocoapods-try         : 1.2.0
```

### Error

```
RuntimeError - `PBXGroup` attempted to initialize an object with unknown ISA `PBXFileSystemSynchronizedRootGroup` from attributes: `{"isa"=>"PBXFileSystemSynchronizedRootGroup", "path"=>"MyApp", "sourceTree"=>"<group>"}`
If this ISA was generated by Xcode please file an issue: https://github.com/CocoaPods/Xcodeproj/issues/new
/Users/loicsharma/homebrew/lib/ruby/gems/3.3.0/gems/xcodeproj-1.24.0/lib/xcodeproj/project/object.rb:359:in `rescue in object_with_uuid'
/Users/loicsharma/homebrew/lib/ruby/gems/3.3.0/gems/xcodeproj-1.24.0/lib/xcodeproj/project/object.rb:349:in `object_with_uuid'
/Users/loicsharma/homebrew/lib/ruby/gems/3.3.0/gems/xcodeproj-1.24.0/lib/xcodeproj/project/object.rb:300:in `block (2 levels) in configure_with_plist'
/Users/loicsharma/homebrew/lib/ruby/gems/3.3.0/gems/xcodeproj-1.24.0/lib/xcodeproj/project/object.rb:299:in `each'
/Users/loicsharma/homebrew/lib/ruby/gems/3.3.0/gems/xcodeproj-1.24.0/lib/xcodeproj/project/object.rb:299:in `block in configure_with_plist'
/Users/loicsharma/homebrew/lib/ruby/gems/3.3.0/gems/xcodeproj-1.24.0/lib/xcodeproj/project/object.rb:296:in `each'
/Users/loicsharma/homebrew/lib/ruby/gems/3.3.0/gems/xcodeproj-1.24.0/lib/xcodeproj/project/object.rb:296:in `configure_with_plist'
/Users/loicsharma/homebrew/lib/ruby/gems/3.3.0/gems/xcodeproj-1.24.0/lib/xcodeproj/project.rb:272:in `new_from_plist'
/Users/loicsharma/homebrew/lib/ruby/gems/3.3.0/gems/xcodeproj-1.24.0/lib/xcodeproj/project/object.rb:350:in `object_with_uuid'
/Users/loicsharma/homebrew/lib/ruby/gems/3.3.0/gems/xcodeproj-1.24.0/lib/xcodeproj/project/object.rb:290:in `block in configure_with_plist'
/Users/loicsharma/homebrew/lib/ruby/gems/3.3.0/gems/xcodeproj-1.24.0/lib/xcodeproj/project/object.rb:287:in `each'
/Users/loicsharma/homebrew/lib/ruby/gems/3.3.0/gems/xcodeproj-1.24.0/lib/xcodeproj/project/object.rb:287:in `configure_with_plist'
/Users/loicsharma/homebrew/lib/ruby/gems/3.3.0/gems/xcodeproj-1.24.0/lib/xcodeproj/project.rb:272:in `new_from_plist'
/Users/loicsharma/homebrew/lib/ruby/gems/3.3.0/gems/xcodeproj-1.24.0/lib/xcodeproj/project.rb:213:in `initialize_from_file'
/Users/loicsharma/homebrew/lib/ruby/gems/3.3.0/gems/xcodeproj-1.24.0/lib/xcodeproj/project.rb:113:in `open'
/Users/loicsharma/homebrew/lib/ruby/gems/3.3.0/gems/cocoapods-1.15.2/lib/cocoapods/command/init.rb:41:in `validate!'
/Users/loicsharma/homebrew/lib/ruby/gems/3.3.0/gems/claide-1.1.0/lib/claide/command.rb:333:in `run'
/Users/loicsharma/homebrew/lib/ruby/gems/3.3.0/gems/cocoapods-1.15.2/lib/cocoapods/command.rb:52:in `run'
/Users/loicsharma/homebrew/lib/ruby/gems/3.3.0/gems/cocoapods-1.15.2/bin/pod:55:in `<top (required)>'
/Users/loicsharma/homebrew/lib/ruby/gems/3.3.0/bin/pod:25:in `load'
/Users/loicsharma/homebrew/lib/ruby/gems/3.3.0/bin/pod:25:in `<main>'
```

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[!] Oh no, an error occurred.

Search for existing GitHub issues similar to yours:
https://github.com/CocoaPods/CocoaPods/search?q=%60PBXGroup%60+attempted+to+initialize+an+object+with+unknown+ISA+%60PBXFileSystemSynchronizedRootGroup%60+from+attributes%3A+%60%7B%22isa%22%3D%3E%22PBXFileSystemSynchronizedRootGroup%22%2C+%22path%22%3D%3E%22MyApp%22%2C+%22sourceTree%22%3D%3E%22%3Cgroup%3E%22%7D%60%0AIf+this+ISA+was+generated+by+Xcode+please+file+an+issue%3A+https%3A%2F%2Fgithub.com%2FCocoaPods%2FXcodeproj%2Fissues%2Fnew&type=Issues

If none exists, create a ticket, with the template displayed above, on:
https://github.com/CocoaPods/CocoaPods/issues/new

Be sure to first read the contributing guide for details on how to properly submit a ticket:
https://github.com/CocoaPods/CocoaPods/blob/master/CONTRIBUTING.md

Don't forget to anonymize any private data!

Looking for related issues on cocoapods/cocoapods...
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````

</details>