100 Days of SwiftUI - Day 82

It’s day 82 of the 100 Days of SwiftUI! Yesterday, we learned about implementing notifications, creating custom context menus and more. Today, we’re focussing on building a tab bar and sharing data across tabs. Let’s dive in!

Table of Contents

Building our tab bar in SwiftUI

This app is going to display four SwiftUI views inside a tab bar: one to show everyone that you met, one to show people you have contacted, another to show people you haven’t contacted, and a final one showing your personal information for others to scan.
Those first three views are variations on the same concept, but the last one is quite different. As a result, we can represent all our UI with just three views: one to display people, one to show our data, and one to bring all the others together using TabView.
Hacking with Swift, Paul Hudson (@twostraws)

Sharing data across tabs using @EnvironmentObject

We’ve seen how we can share data across views. This is very useful, essential even, when building apps, as it allows us to keep re-using the same piece of data without making tons of objects. We can also share data across tabs, which is useful in the same way.

SwiftUI’s environment lets us share data in a really beautiful way: any view can send objects into the environment, then any child view can read those objects back out from the environment at a later date. Even better, if one view changes the object all other views automatically get updated – it’s an incredibly smart way to share data in larger applications.
In our app we have a TabView that contains three instances of ProspectsView, and we want all three of those to work as different views on the same shared data. This is a great example of where SwiftUI’s environment makes sense: we can define a class that stores one prospect, then place an array of those prospects into the environment so all our views can read it if needed.
Hacking with Swift, Paul Hudson (@twostraws)