Support App Extension

SVProgressHUD#991
https://github.com/tobihagemann/SVProgressHUD/blob/2.2.x/SVProgressHUD.podspec

SVProgressHUD.podspec

@@ -1,7 +1,7 @@
 Pod::Spec.new do |s|
   s.name     = 'SVProgressHUD'
-  s.version  = '2.2.6'
-  s.ios.deployment_target = '8.3'
+  s.version  = '2.2.5'
+  s.ios.deployment_target = '8.0'
   s.tvos.deployment_target = '9.0'
   s.license  =  { :type => 'MIT', :file => 'LICENSE' }
   s.summary  = 'A clean and lightweight progress HUD for your iOS and tvOS app.'
@@ -11,8 +11,19 @@ Pod::Spec.new do |s|
 
   s.description = 'SVProgressHUD is a clean and easy-to-use HUD meant to display the progress of an ongoing task on iOS and tvOS. The success and error icons are from Freepik from Flaticon and are licensed under Creative Commons BY 3.0.'
 
-  s.source_files = 'SVProgressHUD/*.{h,m}'
   s.framework    = 'QuartzCore'
-  s.resources    = 'SVProgressHUD/SVProgressHUD.bundle'
   s.requires_arc = true
+
+  s.default_subspec = 'Core'
+
+  s.subspec 'Core' do |core|
+    core.source_files = 'SVProgressHUD/*.{h,m}'
+    core.resources = 'SVProgressHUD/SVProgressHUD.bundle'
+  end
+
+  s.subspec 'AppExtension' do |ext|
+    ext.source_files = 'SVProgressHUD/*.{h,m}'
+    ext.resources = 'SVProgressHUD/SVProgressHUD.bundle'
+    ext.pod_target_xcconfig = { 'GCC_PREPROCESSOR_DEFINITIONS' => 'SV_APP_EXTENSIONS=1' }
+  end
 end