How to launch Native App from Web app in iPhone?

I want to access TTS (Text-To-Speech) and STT (Speech-To-Text) functionality of iOS from web app. Since web app dont access ios device functions, is it possible to launch Native app from Web app? e.g. When user wants to access TTS (e.g. Dragon Dictation), web page 开发者_如何学运维will launch Native app, take recording and send the recorded text to web app again.

Or we can access TTS/STT functionality right from web app?

The only native apps you can access from web apps are those with custom URL schemes set up, and the built-in ones e.g. SMS (sms://), phone (tel://), iTunes (itms://) and YouTube (http://youtube.com/watch?...).

If the apps you mention don't have their own custom URL schemes which you can use to get to them, there's no other way you can do this.

I can answer one part of your question - using the functionality of an IOS native app from a web-app;

Apps can be developed such that they respond to custom URL schemes - like, for example, the mail app responds to mailto:// and youtube responds to youtube://. Calling a URL with one of these schemes will start the IOS app - but it's entirely on the developer to code this into their application.

You could therefore in theory develop an app to get triggered from a web-app, perform an action then return to a web app after! Probably not something I would try and do though.