For example this ionic calender(https://github.com/twinssbc/Ionic-Calendar), is there any way that we can convert it for Ionic 2 or use it as Angular1 directive?
I’m pretty sure this beautiful community knows how to do that practically.
Angular1 directives are pretty much useless in Angular2.
So you mean we need to rewrite whole directives right?
Yes. The framework structure is radically different.
take a look at the angular 2 migration tool - ngUpgrade. There you can mix a1 and a2 to upgrade your app step by step