Creating a menu in Ionic 4 should be simple and the process seems to be well documented but I struggled with it longer than I should have. Therefore, I decided to share my findings for my future self and for everyone else who might find this helpful.
Posts about Ionic 4
Angular supports several different modes of encapsulating styles in components so that styles from one component don't affect elements in other components. By default, Angular uses ViewEncapsulation.Emulated to emulate native Shadow DOM behavior without actually using Shadow DOM. Ionic 4 uses the same default which can cause problems when upgrading applications from Ionic 3 where ViewEncapsulation.None was used.
Ionic has built-in support for navigating back using the swipe gesture. If you want to disable it for the whole application, you can pass a configuration option to IonicModule. Alternatively, you can disable and re-enable swipeback navigation ar runtime. In Ionic 3, NavController exposed a property for that. In Ionic 4, NavController doesn't provide such a property anymore. Instead, IonRouterOutlet now has an equivalent swipeGesture property.
In Ionic 4, the dismissAll method for closing all currently open loading overlays has been removed. This might not be such a bad idea since it could cause problems when used carelessly. Still, when porting an existing Ionic 3 app to Ionic 4 not having an equivalent for it available can be a problem. I created my own replacement to make porting easier and minimize the required code changes.
In Ionic 3, there was an easy way to automatically dismiss a loading overlay when the navigation to a new page completed - you only had to set the dismissOnPageChange flag when creating the overlay. There's no such flag available in Ionic 4.
Last year I wrote a blog post about making code for displaying alerts reusable and testable by wrapping it into a function which returns the user's response as a promise. The sample was written in Ionic 3. The code doesn't work in Ionic 4 without modifications. Since I recently received a request for an Ionic 4 version of the code, I decided to write this follow-up post.
The final release of Ionic 4 is a good incentive for migrating existing Ionic 2/3 applications to Ionic 4. The official documentation lists the required steps for creating a new Ionic 4 project and adding Android support to it. If you're using Cordova 8+, then the application will run fine. But if you're still using Cordova 7.1.0, you'll only be greeted by a white screen when the application starts.