[MBL-1453] PagedTabBar implementation and adding to PagedContainerViewController

[stevestreza-ksr]

📲 What

Reimplements the paged tab bar look in SwiftUI, integrates it into Amy's existing PagedContainerViewController, and adds tests for it.

🛠 How

The PagedTabBar takes a list of instances of TabBarPage items, a basic protocol that has a name and badge count. It uses the PagedContainerViewModel for determining which tab to show.

The PagedContainerViewModel was cleaned up and had nearly all calls to index-based pages removed in favor of returning the TabBarPage instances. This should prevent worrying about over-indexing and risking runtime crashes.

The new PagedTabBar has some screenshot tests and the PagedContainerViewModel has had some unit tests added.

Note: Originally there was a separate PagedTabBarViewModel that worked together with the PagedContainerViewModel, but this ended up being way too easy to accidentally end up with an infinitely recursive scenario where the PagedTabBarViewModel called the PagedContainerViewModel which called the PagedTabBarViewModel which called … [etc]. Since they are both relying on reactivity to update UI, for now they just use the same view model.

👀 See

Figma and the screenshot at the top of the screen

♿️ Accessibility

• Tap targets use minimum of 44x44 pts dimensions
• Works with VoiceOver
• Supports Dynamic Type

✅ Acceptance criteria

• [x]Built in SwiftUI or UIKit (developer’s choice; the container screen is a UIViewController)
• N/A: Could possibly be reused from SortPagerViewController
• Gracefully displays arbitrary titles and badges, even with long tab names (i.e. German)
• Supports basic accessibility needs (adaptive fonts, VoiceOver)
• Animates pleasingly when tabs are switched
• Provides an appropriate delegate / callback / binding method so that a view using the tab bar knows when the tabs are swapped

⏰ TODO

• Animation. Tried a few techniques for doing this but was having trouble getting SwiftUI to not break when doing them. May have to spin this into a fast-follow task.

[ifosli]

Nice! I left a few comments, but overall I like it! I am quite concerned by the reliance on a badge number, though, since we're not going to get that on the user object for milestone 1. It might be worth confirming with Alison what we want this to look like for now before getting rid of it entirely, though. (I'm not actually sure if we'll want to show the count on the activity tab only - it'd be useful info but it'd look kinda weird.) If you do have an idea for how to get the badge number for the project alerts I'm happy to approve this pr as is; just let me know!

[nativeksr]

	1 Warning
⚠️	Big PR

Generated by 🚫 Danger

[ifosli]

Looks great!!