iOS-Onboarding

2024 iOS Onboarding Project (WIP)

Sourced from this YouTube Tutorial Series

All credit goes to Swiftful Thinking (a fantastic resource)!

Setup

Git

Getting an SSH key:

Run these commands in your terminal (note you should change your email in the second command)

ssh_key_file=~/.ssh/iOSTeam

ssh-keygen -t ed25519 -C "your_github_email" -f $ssh_key_file

eval "$(ssh-agent -s)"

ssh-add $ssh_key_file

cat $ssh_key_file.pub | pbcopy

• Go to https://github.com/settings/keys and login.
• Click ’New SSH key’ and add your copied public key and a title (i.e. “iOS key”).
• Add the following lines to the file ~/.ssh/config (create it if it doesn’t exist):

Host github.com
    ForwardAgent yes
    IdentityFile ~/.ssh/iOSTeam

Cloning the repository:

git clone [email protected]:michiganhackers/iOS-Onboarding.git

Making your branch:

git checkout -b your_name

Before you leave (skip this at the start):

git add .
git commit -m "Your commit message here"
git push

Ask Finn or Parker if you have any questions!!

Xcode

• Download the latest version of Xcode from the App Store
• Open Xcode
• Create New Project
• Select iOS, select App, select Next
• Product name: Map, select Next
• Store the project in the iOS-Onboarding folder you cloned
• Select create

What's in the basic App template?

1. MapApp.swift: This performs an initial set up, then creates and displays your initial view.
2. ContentView.swift: This is our initial piece of user interface.
3. Assets.xcassets: This is an asset catalog, which stores all the images and colors used in our project.
4. Preview Content folder containing a Preview Assets catalog.
5. Template code for writing tests.

The part we really care about ContentView.swift. This file contains the code that is shown on the screen.

First, though: what makes ContentView.swift get shown on the screen?

Open MapApp.swift.

That code creates a new ContentView instance and places it inside a window group so it’s visible onscreen.

Open ContentView.swift and let’s look at some actual SwiftUI code.

ContentView conforms to the View protocol. Everything you want to show in SwiftUI needs to conform to View, and really that means only one thing: you need to have a property called body that returns some sort of View.

The return type of body is some View. The some keyword was introduced in Swift 5.1 and is part of a feature called opaque return types, and in this case what it means is literally “this will return some sort of View but SwiftUI doesn’t need to know (or care) what.”

Inside the body property there’s a vertical stack (VStack) of content showing an image and some text.

That stack has a padding() method call below it. In SwiftUI this actually creates a new view with padding around it, rather than changing the existing stack. As a result, we refer to functions like padding() as modifiers because they create modified content. There are also modifiers to make the image scale bigger and change its color for example.

Finally, below ContentView is #Preview, which marks special code to display our view an interactive preview of our view inside Xcode. Right now this creates an instance of ContentView, but you can customize these if you need to.

Importing Assets

There are some assets included in the Data folder for use in your project.

• Right click the Assets folder in your Map project (Clicking the folder in the top left shows the "Project Navigator"), click Delete and click Move to Trash
• Drag and drop the Assets.xcassets folder in the Data folder of the cloned repository into your project navigatior, check "Copy items if needed" and click Finish
• Click on Assets in your Project Navigator in Xcode and look around inside the folder

MVVM

Here is what ChatGPT has to say about MVVM:

MVVM stands for Model-View-ViewModel, and it is an architectural design pattern
commonly used in Swift development (and other programming languages) to
organize and structure code in a way that separates concerns and promotes
maintainability. Here's a brief overview of each component in MVVM:

    Model: Represents the data and business logic of the application. It is
responsible for retrieving, processing, and storing data. In a Swift
application, models are often Swift classes or structs.

    View: Represents the user interface and is responsible for displaying the
data to the user. In the context of iOS development with Swift, views are
typically implemented as UIView or UIViewController instances.

    ViewModel: Acts as an intermediary between the model and the view. It
transforms the data from the model into a format that can be easily presented
by the view. The ViewModel does not have a direct reference to the view;
instead, it exposes data and commands that the view can bind to. This helps in
separating the presentation logic from the UI.

In the MVVM pattern, the flow of data is typically unidirectional: from the
model to the ViewModel, and from the ViewModel to the View. This separation of
concerns makes the codebase more modular, testable, and easier to maintain.
Additionally, it facilitates the use of data binding, where changes in the
ViewModel are automatically reflected in the associated View, and vice versa.

• Right click in the Project Navigator and click "New Group" to create a new folder
• Create 3 folders called "Views", "ViewModels", and "Models"

Creating Models for each location

• Right click Models
• New File
• Swift File, Next
• Call it Location, create
• Inside of the new file create a struct called Location

What data do we need to store in each Location?

The provided LocationDataService file contains an array of Location structs, (go ahead and look inside this file).

One instantiation of a Location look as follows:

Location(
            name: "Colosseum",
            cityName: "Rome",
            coordinates: CLLocationCoordinate2D(latitude: 41.8902, longitude:
12.4922),
            description: "The Colosseum is an oval amphitheatre in the centre
of the city of Rome, Italy, just east of the Roman Forum. It is the largest
ancient amphitheatre ever built, and is still the largest standing amphitheatre
in the world today, despite its age.",
            imageNames: [
                "rome-colosseum-1",
                "rome-colosseum-2",
                "rome-colosseum-3",
            ],
            link: "https://en.wikipedia.org/wiki/Colosseum")

Here you can see what properties we plan to store in each Location struct.

Add each these properties to your Location struct like so:

struct Location {
    let name: String
}

The let keyword defines a constant (var defines a mutable/variable type) and :String specifies the type of the constant as a String.

Swift is a dynamically typed language, meaning the compiler can figure out the types of the variables when they are given values. This means if we were to give name a default value, by writing say let name = "Michigan", we wouldn't have to specify that the type is a String.

Finish the rest of the struct, note the type: "CLLocationCoordinate2D" is defined in the MapKit library so, you should write import MapKit above the struct.

Also note imageNames is an array, so you should define its type in a similar manner to the following (but not an int):

let numbers: [Int]

Ask Finn if you have any questions.

Add DataServices

• Make a new folder called DataServices
• Drag and drop the LocationsDataServices file from the "Data" folder into your new DataServices folder, again making sure to copy if needed.

Note: since we created the Location struct, this file shouldn't cause any compiler errors.

Our first View and ViewModel

• Add a new file to Views called LocationsView, this time selecting "SwiftUI View" instead of "Swift File"
• Add a new (regular swift file) file to ViewModels called LocationsViewModel

Make a class called LocationsViewModel and have it "conform" to the ObservableObject "protocol" like so:

class LocationsViewModel: ObservableObject {
    
}

• What is the difference between class and struct in swift? Do a quick google search.

Notice how the above syntax looks similar to the excplicit defining of data types we used earlier.

What this does is allows the changes to the properties of our class to trigger updates to the user interface.

Protocols can be thought of as "Types" of classes. For a class to conform to a protocol, it means the class is guaranteed to define certain functions and properties specified by the function.

Now lets add a variable to this viewmodel to store the array of locations defined in LocationsDataService like so:

@Published var locations: [Location]

The @Pulbished wrapper makes it so the locations variable "announces" to the rest of the program when it changes, allowing it to be updated on the screen.

We can also add an init() constructor to the class to intilize the locations variable with the array in LocationsDataService like so:

init() {
    let locations = LocationsDataService.locations
    self.locations = locations
}

Using our ViewModel

Inside of our LocationsView file, lets try to display the locations in a list.

Lets create an instance of our LocationsViewModel at the top of our struct like so:

@StateObject private var vm = LocationsViewModel()

-- Temporary end of Tutorial --- Go to the video playlist linked at the top, video #2 to continue