Bing for iOS from Microsoft is not just an app for web search, it has Bing Translator feature that allows you to quickly translate foreign web page. To make it convenient for users, Microsoft has created a “Bing Translator” action extension for a quick language translation.
To get started, first install the Bing app from the Apple App Store. Action extension requires iOS 8. Once the Bing app is on your iPhone, you can access the “Bing Translator” action on all apps that support the share sheet for a web link.
Take Safari mobile as an example. Visit a foreign page, tap the Share button on the toolbar and select the “Bing Translator” on the share sheet to start the translation.
If you do not see the “Bing Translator” button, scroll all the way to the right, tap on the “More” button, and turn on the switch for “Bing Translator”.