Add podspec

ReactNativeShareExtension.podspec

@@ -0,0 +1,22 @@
+require 'json'
+
+package = JSON.parse(File.read(File.join(__dir__, 'package.json')))
+
+Pod::Spec.new do |s|
+  s.name         = "ReactNativeShareExtension"
+  s.version      = package['version']
+  s.summary      = package['description']
+  s.license      = package['license']
+
+  s.authors      = package['author']
+  s.homepage     = package['repository']['url']
+  s.platform     = :ios, "9.0"
+  s.ios.deployment_target = '9.0'
+  s.tvos.deployment_target = '10.0'
+
+  s.source       = { :git => "https://github.com/WorldBrain/react-native-share-extension.git", :tag => "master" }
+  s.source_files  = "ios/**/*.{h,m}"
+
+  s.dependency 'React'
+end
+