When Apple introduced iOS, the original app recommendation was to use HTML5, CSS3, and JavaScript to create rich client-side user experiences. Apple has not removed web app support and has enhanced some capabilities over time. The iOS web app experience is driven by custom metadata that's added to a web page's HEAD.
Much of the Apple meta data has served as a model for the modern web manifest specification. Before the web manifest specification was created, Chrome on Android integrated support for the Apple meta data to drive a similar experience.
The web app experience on iOS is triggered when your website contains Apple-specific META tags, corresponding icons, and when the user has added your site to their homescreen.
The first piece you need is a png file as the default homescreen icon. The file should be named apple-touch-icon...
