Building Blocks in the logical application domain
Mobile apps typically provide a "refresh" key `F5` substitute by pulling down from the top of the page. Here is how to do this in Ionic 3.
When the callback of an asynchronous function is executed there is no determined state of $this. So better supply a copy.
Reacting to events is a fundamental paradigm in any software architecture. Here is one approach how to do this with Cordova events in Ionic 3.