请问关于cocoapod与libffi的问题

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请问大家谁用过libffi这个东西，现在发现创建自定义的pod时，libffi无法通过验证(pod spec lint)。目前公司很多项目用到BlocksKit这个库，它本身使用libffi。因此弄得现在无法更新这些项目了。一时找不到解决方案。

以下就是基本的控制台输出：
ricols-MacBook-Pro:MyPodExample ricolwang$ cat MyPodExample.podspec
Pod::Spec.new do |s|
s.name = "MyPodExample"
s.version = "0.0.1"
s.platform = :ios, "6.1"
s.summary = "This is an example to show how to create a cocoapod"
s.description = <<-DESC
A longer description of MyPodExample in Markdown format.

* Think: Why did you write this? What is the focus? What does it do?
* CocoaPods will be using this to generate tags, and improve search results.
* Try to keep it short, snappy and to the point.
* Finally, don't worry about the indent, CocoaPods strips it!
DESC
s.homepage = "https://bitbucket.org"
s.license = { :type => "RMIT", :text => "this is a test!" }
s.author = { "Ricol Wang" => "[e-mail]" }
s.source = { :git => "https://[e-mail]/wangxinghe/mypodexample.git", :tag => "0.0.1" }
s.source_files = "MyPodExample/MyObject.{h,m}"
s.requires_arc = true
s.dependency 'libffi'
end
ricols-MacBook-Pro:MyPodExample ricolwang$ pod spec lint MyPodExample.podspec

-> MyPodExample (0.0.1)
- NOTE | [xcodebuild] libffi/ios/src/arm/ffi.c:325:21: warning: ambiguous expansion of macro 'alloca' [-Wambiguous-macro]
- NOTE | [xcodebuild] /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS7.1.sdk/usr/include/alloca.h:39:9: note: expanding this definition of 'alloca'
- NOTE | [xcodebuild] libffi/ios/include/ffi_common.h:24:10: note: other definition of 'alloca'
- NOTE | [xcodebuild] libffi/ios/src/arm/ffi.c:332:21: warning: ambiguous expansion of macro 'alloca' [-Wambiguous-macro]
- NOTE | [xcodebuild] libffi/ios/src/arm/ffi.c:381:26: warning: ambiguous expansion of macro 'alloca' [-Wambiguous-macro]
- ERROR | [xcodebuild] libffi/ios/include/ffi_common.h:77:1: error: unknown type name 'ffi_status'
- ERROR | [xcodebuild] libffi/ios/include/ffi_common.h:77:33: error: unknown type name 'ffi_cif'
- ERROR | [xcodebuild] libffi/ios/include/ffi_common.h:78:1: error: unknown type name 'ffi_status'
- ERROR | [xcodebuild] libffi/ios/include/ffi_common.h:78:37: error: unknown type name 'ffi_cif'
- ERROR | [xcodebuild] libffi/ios/include/ffi_common.h:84:3: error: unknown type name 'ffi_cif'
- ERROR | [iOS] [xcodebuild] libffi/ios/src/debug.c:50:20: error: unknown type name 'ffi_type'

Analyzed 1 podspec.

[!] The spec did not pass validation.
ricols-MacBook-Pro:MyPodExample ricolwang$