WWDC23 SALE: Save 50% on all my Swift books and bundles! >>

Moonshot: Wrap up

Paul Hudson    @twostraws   

This app is the most complex one we’ve built so far. Yes, there are multiple views, but we also strayed away from lists and forms and into our own scrolling layouts, using GeometryReader to get precise sizes to make the most of our space.

But this was also the most complex Swift code we’ve written so far – generics are an incredibly powerful feature, and once you add in constraints you open up a huge range of functionality that lets you save time while also gaining flexibility.

You’re also now starting to see how useful Codable is: its ability to decode a hierarchy of data in one pass is invaluable, which is why it’s central to so many Swift apps.

Review what you learned

Anyone can sit through a tutorial, but it takes actual work to remember what was taught. It’s my job to make sure you take as much from these tutorials as possible, so I’ve prepared a short review to help you check your learning.

Click here to review what you learned in this project.


One of the best ways to learn is to write your own code as often as possible, so here are three ways you should try extending this app to make sure you fully understand what’s going on.

  1. Add the launch date to MissionView, below the mission badge. You might choose to format this differently given that more space is available, but it’s down to you.
  2. Extract one or two pieces of view code into their own new SwiftUI views – the horizontal scroll view in MissionView is a great candidate, but if you followed my styling then you could also move the Rectangle dividers out too.
  3. For a tough challenge, add a toolbar item to ContentView that toggles between showing missions as a grid and as a list.

Hacking with Swift+ subscribers can get a complete video solution for this checkpoint here: Solution to Moonshot. If you don’t already subscribe, you can start a free trial today.

Tip: For that last one, your best bet is to make all your grid code and all your list code two separate views, and switch between them using an if condition in ContentView. You can’t attach SwiftUI modifiers to an if condition, but you can wrap that condition in a Group then attach modifiers to there, like this:

Group {
    if showingGrid {
        GridLayout(astronauts: astronauts, missions: missions)
    } else {
        ListLayout(astronauts: astronauts, missions: missions)
.navigationTitle("My Group")

You might hit some speed bumps trying to style your list, because they have a particular look and feel on iOS by default. Try attaching .listStyle(.plain) to your list, then something like .listRowBackground(Color.darkBackground) to the contents of your list row – that should get you a long way towards your goal.

Save 50% in my WWDC23 sale.

SAVE 50% To celebrate WWDC23, all our books and bundles are half price, so you can take your Swift knowledge further without spending big! Get the Swift Power Pack to build your iOS career faster, get the Swift Platform Pack to builds apps for macOS, watchOS, and beyond, or get the Swift Plus Pack to learn advanced design patterns, testing skills, and more.

Save 50% on all our books and bundles!

Buy Pro Swift Buy Pro SwiftUI Buy Swift Design Patterns Buy Testing Swift Buy Hacking with iOS Buy Swift Coding Challenges Buy Swift on Sundays Volume One Buy Server-Side Swift Buy Advanced iOS Volume One Buy Advanced iOS Volume Two Buy Advanced iOS Volume Three Buy Hacking with watchOS Buy Hacking with tvOS Buy Hacking with macOS Buy Dive Into SpriteKit Buy Swift in Sixty Seconds Buy Objective-C for Swift Developers Buy Beyond Code

Was this page useful? Let us know!

Average rating: 4.9/5

Unknown user

You are not logged in

Log in or create account

Link copied to your pasteboard.