Error running pod install for Qt application (iOS)

Hi,

i try to use 'Braintree' in my Qt iOS app.

When running

pod install

i get the following error:

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### Command

```
/usr/local/bin/pod install
```
### Report
- What did you do?
- What did you expect to happen?
- What happened instead?
### Stack

```
CocoaPods : 0.39.0
Ruby : ruby 2.0.0p645 (2015-04-13 revision 50299) [universal.x86_64-darwin15]
RubyGems : 2.0.14
Host : Mac OS X 10.11.2 (15C50)
Xcode : 7.2 (7C68)
Git : git version 2.5.4 (Apple Git-61)
Ruby lib dir : /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib
Repositories : master - https://github.com/CocoaPods/Specs.git @ 069d75d79a146b0ab057c083cf99aa651833df70
```
### Plugins

```
cocoapods-plugins : 0.4.2
cocoapods-search : 0.1.0
cocoapods-stats : 0.6.2
cocoapods-trunk : 0.6.4
cocoapods-try : 0.5.1
```
### Podfile

``` ruby
pod 'Braintree'
```
### Error

```
RuntimeError - [!] Xcodeproj doesn't know about the following attributes {"refType"=>"0"} for the 'PBXFileReference' isa.
If this attribute was generated by Xcode please file an issue: https://github.com/CocoaPods/Xcodeproj/issues/new
/Library/Ruby/Gems/2.0.0/gems/xcodeproj-0.28.2/lib/xcodeproj/project/object.rb:308:in `configure_with_plist'
/Library/Ruby/Gems/2.0.0/gems/xcodeproj-0.28.2/lib/xcodeproj/project.rb:250:in `new_from_plist'
/Library/Ruby/Gems/2.0.0/gems/xcodeproj-0.28.2/lib/xcodeproj/project/object.rb:337:in `object_with_uuid'
/Library/Ruby/Gems/2.0.0/gems/xcodeproj-0.28.2/lib/xcodeproj/project/object.rb:287:in `block (2 levels) in configure_with_plist'
/Library/Ruby/Gems/2.0.0/gems/xcodeproj-0.28.2/lib/xcodeproj/project/object.rb:286:in `each'
/Library/Ruby/Gems/2.0.0/gems/xcodeproj-0.28.2/lib/xcodeproj/project/object.rb:286:in `block in configure_with_plist'
/Library/Ruby/Gems/2.0.0/gems/xcodeproj-0.28.2/lib/xcodeproj/project/object.rb:283:in `each'
/Library/Ruby/Gems/2.0.0/gems/xcodeproj-0.28.2/lib/xcodeproj/project/object.rb:283:in `configure_with_plist'
/Library/Ruby/Gems/2.0.0/gems/xcodeproj-0.28.2/lib/xcodeproj/project.rb:250:in `new_from_plist'
/Library/Ruby/Gems/2.0.0/gems/xcodeproj-0.28.2/lib/xcodeproj/project/object.rb:337:in `object_with_uuid'
/Library/Ruby/Gems/2.0.0/gems/xcodeproj-0.28.2/lib/xcodeproj/project/object.rb:287:in `block (2 levels) in configure_with_plist'
/Library/Ruby/Gems/2.0.0/gems/xcodeproj-0.28.2/lib/xcodeproj/project/object.rb:286:in `each'
/Library/Ruby/Gems/2.0.0/gems/xcodeproj-0.28.2/lib/xcodeproj/project/object.rb:286:in `block in configure_with_plist'
/Library/Ruby/Gems/2.0.0/gems/xcodeproj-0.28.2/lib/xcodeproj/project/object.rb:283:in `each'
/Library/Ruby/Gems/2.0.0/gems/xcodeproj-0.28.2/lib/xcodeproj/project/object.rb:283:in `configure_with_plist'
/Library/Ruby/Gems/2.0.0/gems/xcodeproj-0.28.2/lib/xcodeproj/project.rb:250:in `new_from_plist'
/Library/Ruby/Gems/2.0.0/gems/xcodeproj-0.28.2/lib/xcodeproj/project/object.rb:337:in `object_with_uuid'
/Library/Ruby/Gems/2.0.0/gems/xcodeproj-0.28.2/lib/xcodeproj/project/object.rb:277:in `block in configure_with_plist'
/Library/Ruby/Gems/2.0.0/gems/xcodeproj-0.28.2/lib/xcodeproj/project/object.rb:274:in `each'
/Library/Ruby/Gems/2.0.0/gems/xcodeproj-0.28.2/lib/xcodeproj/project/object.rb:274:in `configure_with_plist'
/Library/Ruby/Gems/2.0.0/gems/xcodeproj-0.28.2/lib/xcodeproj/project.rb:250:in `new_from_plist'
/Library/Ruby/Gems/2.0.0/gems/xcodeproj-0.28.2/lib/xcodeproj/project.rb:195:in `initialize_from_file'
/Library/Ruby/Gems/2.0.0/gems/xcodeproj-0.28.2/lib/xcodeproj/project.rb:95:in `open'
/Library/Ruby/Gems/2.0.0/gems/cocoapods-0.39.0/lib/cocoapods/installer/analyzer/target_inspector.rb:32:in `compute_results'
/Library/Ruby/Gems/2.0.0/gems/cocoapods-0.39.0/lib/cocoapods/installer/analyzer.rb:659:in `block (2 levels) in inspect_targets_to_integrate'
/Library/Ruby/Gems/2.0.0/gems/cocoapods-0.39.0/lib/cocoapods/installer/analyzer.rb:657:in `each'
/Library/Ruby/Gems/2.0.0/gems/cocoapods-0.39.0/lib/cocoapods/installer/analyzer.rb:657:in `block in inspect_targets_to_integrate'
/Library/Ruby/Gems/2.0.0/gems/cocoapods-0.39.0/lib/cocoapods/user_interface.rb:59:in `section'
/Library/Ruby/Gems/2.0.0/gems/cocoapods-0.39.0/lib/cocoapods/installer/analyzer.rb:656:in `inspect_targets_to_integrate'
/Library/Ruby/Gems/2.0.0/gems/cocoapods-0.39.0/lib/cocoapods/installer/analyzer.rb:61:in `analyze'
/Library/Ruby/Gems/2.0.0/gems/cocoapods-0.39.0/lib/cocoapods/installer.rb:213:in `analyze'
/Library/Ruby/Gems/2.0.0/gems/cocoapods-0.39.0/lib/cocoapods/installer.rb:136:in `block in resolve_dependencies'
/Library/Ruby/Gems/2.0.0/gems/cocoapods-0.39.0/lib/cocoapods/user_interface.rb:59:in `section'
/Library/Ruby/Gems/2.0.0/gems/cocoapods-0.39.0/lib/cocoapods/installer.rb:135:in `resolve_dependencies'
/Library/Ruby/Gems/2.0.0/gems/cocoapods-0.39.0/lib/cocoapods/installer.rb:105:in `install!'
/Library/Ruby/Gems/2.0.0/gems/cocoapods-0.39.0/lib/cocoapods/command/project.rb:71:in `run_install_with_update'
/Library/Ruby/Gems/2.0.0/gems/cocoapods-0.39.0/lib/cocoapods/command/project.rb:101:in `run'
/Library/Ruby/Gems/2.0.0/gems/claide-0.9.1/lib/claide/command.rb:312:in `run'
/Library/Ruby/Gems/2.0.0/gems/cocoapods-0.39.0/lib/cocoapods/command.rb:47:in `run'
/Library/Ruby/Gems/2.0.0/gems/cocoapods-0.39.0/bin/pod:44:in `'
/usr/local/bin/pod:23:in `load'
/usr/local/bin/pod:23:in `'
```

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[!] Oh no, an error occurred.

Greetings
Nando