swift dependency in objc podspec project
<p>I'm creating my first CocoaPod project (ObjC) which requires a Swift dependency. When I try to lint the project I get the error:</p>

<blockquote>
  <p>Pods written in Swift can only be integrated as frameworks; add <code>use_frameworks!</code> to your Podfile or target to opt into using it.</p>
</blockquote>

<p>I understand how to do this when including a CocoaPod in a regular xcode project, but how do I solve this issue when the project is a CocoaPod? I tried adding the 'use_frameworks!' declaration in the podspec file but that doesn't seem to be correct.</p>

<p>Here is my podspec file:</p>

<pre><code>Pod::Spec.new do |s|

  s.name             = "my-custom-pod"
  s.version          = "0.0.1"
  s.summary          = "totally awesome stuff"

  s.description      = &lt;&lt;-DESC
                         more details about the totally awesome stuff, if only it worked :(
                       DESC

  s.homepage         = "https://awesomestuff.com"
  # s.screenshots     = "www.example.com/screenshots_1", "www.example.com/screenshots_2"
  s.license          = 'MIT'
  s.author           = { "Me" =&gt; "me@awesomestuff.com" }
  s.source           = { :git =&gt; "https://awesome.com/awesome/my-custom-pod.git", :tag =&gt; s.version.to_s }
  s.social_media_url = 'https://twitter.com/awesomestuff'

  s.platform     = :ios, '8.0'
  s.requires_arc = true

  s.source_files = 'Pod/Classes/**/*'
  s.resource_bundles = {
    'my-custom-pod' =&gt; ['Pod/Assets/*.png']
  }

  # s.public_header_files = 'Pod/Classes/**/*.h'
  s.frameworks = 'CoreLocation', 'MapKit'
  s.dependency 'SSKeychain', '~&gt; 1.2.3'
  s.dependency 'FMDB', '~&gt; 2.5'
  s.dependency 'GoogleMaps', '~&gt; 1.10.4'
  s.dependency 'Socket.IO-Client-Swift', '~&gt; 4.0.4'
end
</code></pre>

<p>Here, the socket io client is the issue. I'm able to import the socket io framework into my other ObjC projects no problem, but I've never tried to do it into a custom cocoa pod.</p>

<p>Any help is much appreciated. Thanks in advance.</p>