SwiftUI tutorial

SwiftUI 2.0 Cheat Sheet

Using the SwiftUI framework, an iOS, macOS, watchOS, and tvOS app’s user interface can be created by following a SwiftUI tutorial. SwiftUI is Apple’s contemporary and declarative framework for designing more easy and efficient user interfaces.

Creating a simple user interface is a common way that a basic SwiftUI tutorial example introduces the SwiftUI framework. You may create your first SwiftUI view and build up a basic project with the help of the tutorial.

Resource

UIKit equivalent in SwiftUI

UIKit	SwiftUI
UILabel	Text & Label
UIImageView	Image
UITextField	TextField
UITextView	TextEditor
UISwitch	Toggle
UISlider	Slider
UIButton	Button
UITableView	List
UICollectionView	LazyVGrid / LazyHGrid
UINavigationController	NavigationView
UITabBarController	TabView
UIAlertController with style .alert	Alert
UIAlertController with style .actionSheet	ActionSheet
UIStackView with horizontal axis	HStack / LazyHStack
UIStackView with vertical axis	VStack / LazyVStack
UISegmentedControl	Picker
UIStepper	Stepper
UIDatePicker	DatePicker
NSAttributedString	No equivalent (use Text)
MapKit	Map
UIProgressView	ProgressView

View

Text

To show a text in UI simply write:

Text("Hello World")

Screenshot

To add style

Text("Hello World")
    .font(.largeTitle)
    .foregroundColor(Color.green)
    .lineSpacing(50)
    .lineLimit(nil)
    .padding()

Screenshot

To format text inside text view

static let dateFormatter: DateFormatter = {
    let formatter = DateFormatter()
    formatter.dateStyle = .long
    return formatter
}()

var now = Date()
var body: some View {
    Text("Task due date: \(now, formatter: Self.dateFormatter)")
}

Screenshot

Label

Labels are a much-needed addition in the latest SwiftUI iteration. They let you set icons alongside text with the following line of code.

Label("SwiftUI CheatSheet 2.0", systemImage: "up.icloud")

It’s possible to set URL, upon clicking which will redirect to browser.

Link("Click me",destination: URL(string: "your_url")!)

TextEditor

Multi-line scrollable UITextViews natively in SwiftUI

TextEditor(text: $currentText)
                .onChange(of: clearText) { value in
                    if clearText {
                        currentText = ""
                    }
                }

Map

MapKit natively in SwiftUI

Map(mapRect:interactionModes:showsUserLocation: userTrackingMode:

Image

To show image

Image("hello_world") //image name is hello_world

Screenshot

To use system icon

Image(systemName: "cloud.heavyrain.fill")

Screenshot

you can add style to system icon set

Image(systemName: "cloud.heavyrain.fill")
    .foregroundColor(.red)
    .font(.largeTitle)

Screenshot

Add style to Image

Image("hello_world")
    .resizable() //it will sized so that it fills all the available space
    .aspectRatio(contentMode: .fill)
    .padding(.bottom)

Screenshot

Shape

To create Rectangle

Rectangle()
    .fill(Color.red)
    .frame(width: 200, height: 200)

Screenshot

To create circle

Circle()
    .fill(Color.blue)
    .frame(width: 50, height: 50)

Screenshot

ProgressView

To show a ProgressView

ProgressView("Text", value: 10, total: 100)

Layout

Background

To use image as a background

Text("Hello World")
    .font(.largeTitle)
    .background(
        Image("hello_world")
            .resizable()
            .frame(width: 100, height: 100)
    )

Screenshot

Gradient background

Text("Hello World")
    .background(
        LinearGradient(
            gradient: Gradient(colors: [.white, .red, .black]), 
            startPoint: .leading, 
            endPoint: .trailing
        ),
        cornerRadius: 0
    )

Screenshot

VStack

Shows child view vertically

VStack {
    Text("Hello")
    Text("World")
}

Screenshot

Styling

VStack(alignment: .leading, spacing: 20) {
    Text("Hello")
    Divider()
    Text("World")
}

Screenshot

HStack

Shows child view horizontally

HStack {
    Text("Hello")
    Text("World")
}

Screenshot

ZStack

To create overlapping content use ZStack

ZStack() {
    Image("hello_world")
    Text("Hello World")
        .font(.largeTitle)
        .background(Color.black)
        .foregroundColor(.white)
}

Screenshot

LazyVStack

It loads content as and when it’s needed thus improving performance

  ScrollView(.horizontal) {
           LazyVStack(spacing: 10) {
                ForEach(0..<1000) { index in
                    Text("\(index)")
                            .frame(width: 100, height: 200)
                            .border(Color.gray.opacity(0.5), width: 0.5)
                            .background(Color.blue)
                            .cornerRadius(6)
                }
            }
            .padding(.leading, 10)
        }

LazyHStack

It loads content as and when it’s needed thus improving performance

  ScrollView(.horizontal) {
            LazyHStack(spacing: 10) {
                ForEach(0..<1000) { index in
                    Text("\(index)")
                            .frame(width: 100, height: 200)
                            .border(Color.gray.opacity(0.5), width: 0.5)
                            .background(Color.blue)
                            .cornerRadius(6)
                }
            }
            .padding(.leading, 10)
        }

LazyVGrid

A containers for grid-based layouts that let you set child views vertically in LazyVGrid. Each element of a SwiftUI grid is a GridItem. We can set the alignments, spacing, and size of the GridItem

struct ContentView: View {
    
    let colors: [Color] = [.red, .green, .yellow, .blue]
    
    var columns: [GridItem] =
        Array(repeating: .init(.flexible(), alignment: .center), count: 3)
    
    var body: some View {
        ScrollView {
            LazyVGrid(columns: columns, spacing: 10) {
                ForEach(0...100, id: \.self) { index in
                    Text("Tab \(index)")
                        .frame(width: 110, height: 200)
                        .background(colors[index % colors.count])
                    .cornerRadius(8)
                }
            }
        }
    }
}

LazyHGrid

A containers for grid-based layouts that let you set child views horizontally in LazyHGrid

struct ContentView: View {
    
    let colors: [Color] = [.red, .green, .yellow, .blue]
    
    var columns: [GridItem] =
        Array(repeating: .init(.flexible(), alignment: .center), count: 3)
    
    var body: some View {
        ScrollView {
            LazyHGrid(columns: columns, spacing: 10) {
                ForEach(0...100, id: \.self) { index in
                    Text("Tab \(index)")
                        .frame(width: 110, height: 200)
                        .background(colors[index % colors.count])
                    .cornerRadius(8)
                }
            }
        }
    }
}

Input

Toggle

Toggle lets users move between true and false states

@State var isShowing = true //state

Toggle(isOn: $isShowing) {
    Text("Hello World")
}.padding()

Screenshot

Button

To create button

Button(
    action: {
        // do something
    },
    label: { Text("Click Me") }
)

Screenshot

To create image Button

Button(
    action: {
        // do something
    },
    label: { Image("hello_world") }
)

Screenshot

TextField

It heavily relies in state, simply create a state and pass it as it will bind to it

@State var fullName: String = "Joe" //create State

TextField($fullName) // passing it to bind
    .textFieldStyle(.roundedBorder) // adds border

Screenshot

To create secure TextField

@State var password: String = "" // create State

SecureField($password) // passing it to bind
    .textFieldStyle(.roundedBorder) // adds border

Screenshot

Slider

@State var value: Double = 0 // create State
    
Slider(value: $value, from: -100, through: 100, by: 1)

Screenshot

Date Picker

@State var selectedDate = Date()
DatePicker(
    $selectedDate,
    maximumDate: Date(),
    displayedComponents: .date
)

Screenshot

Picker

@State var favoriteColor = 0
var colors = ["Red", "Green", "Blue"]

Picker("Favorite Color", selection: $favoriteColor) {
    ForEach(0 ..< colors.count) { index in
        Text(self.colors[index])
            .tag(index)
    }
}
.pickerStyle(SegmentedPickerStyle())

Screenshot

Stepper

@State var count:Int = 0

Stepper(
    onIncrement: { self.count += 1 }, 
    onDecrement: { self.count -= 1 }, 
    label: { Text("Count is \(count)") }
)

@State var count:Int = 0

Stepper(value: $count, in: 1...10) {
    Text("Count is \(count)")
}

@State private var temperature = 0.0

Stepper(value: $temperature, in: 0...100.0, step: 0.5) {
                Text("Temperature is \(temperature, specifier:"%g")")
            }

Tap

For single tap

Text("Tap me!")
    .onTapGesture {
        print("Tapped!")
    }

For double tap

Text("Tap me!")
    .onTapGesture(count: 2) {
        print("Tapped!")
    }

Screenshot

Gesture

Gesture like TapGesture, LongPressGesture, DragGesture

Text("Tap")
    .gesture(
        TapGesture()
            .onEnded { _ in
                // do something
            }
    )

Text("Drag Me")
    .gesture(
        DragGesture(minimumDistance: 50)
            .onEnded { _ in
                // do something
            }
    )

Text("Long Press")
    .gesture(
        LongPressGesture(minimumDuration: 2)
            .onEnded { _ in
                // do something
            }
    )

OnChange

onChange is a new view modifier that’s available across all SwiftUI views. It lets you listen to state changes and perform actions on a view accordingly.

 TextEditor(text: $currentText)
                .onChange(of: clearText) { value in
                    if clearText{
                        currentText = ""
                    }
                }

List

To create static scrollable List

List {
    Text("Hello world")
    Text("Hello world")
    Text("Hello world")
}

Screenshot

To create dynamic List

let names = ["Thanos", "Iron man", "Ant man"]
List(names, id: \.self) { name in
    Text(name)
}

To add section

List {
    Section(header: Text("Good Hero")) {
        Text("Thanos")
    }

    Section(header: Text("Bad Heros")) {
        Text("Iron man")
    }
}

Screenshot

To make it grouped add .listStyle(GroupedListStyle())

List {
    Section(header: Text("Good Hero")) {
        Text("Thanos")
    }

    Section(header: Text("Bad Heros")) {
        Text("Iron man")
    }
}.listStyle(GroupedListStyle())

Screenshot

To add a footer to a section

List {
    Section(header: Text("Good Heros"), footer: Text("Powerful")){
        Text("Thanos")
    }
    Section(header: Text("Bad Heros"), footer: Text("Not as Powerful")){
        Text("Iron Man")
    }
}.listStyle(GroupedListStyle())

Containers

NavigationView

NavigationView is more/less like UINavigationController, It handles navigation between views, shows title, places navigation bar on top.

NavigationView {
    Text("Hello")
        .navigationBarTitle(Text("World"), displayMode: .inline)
}

Screenshot

For large title use .large

Add bar items to NavigationView

NavigationView {
    Text("Hello")
        .navigationBarTitle(Text("World"), displayMode: .inline)
        .navigationBarItems(
            trailing:
                Button(
                    action: { print("Going to Setting") },
                    label: { Text("Setting") }
                )
        )
}

Screenshot

TabView

TabView creates a container similar to UITabBarController with radio-style selection control which determines which View is presented.

@State private var selection = 0

TabView(selection: $selection) {
    Text("View A")
        .font(.title)
        .tabItemLabel(Text("View A")
            .font(.caption))
        .tag(0)
    Text("View B")
        .font(.title)
        .tabItemLabel(Text("View B")
            .font(.caption))
        .tag(1)
    Text("View C")
        .font(.title)
        .tabItemLabel(Text("View C")
            .font(.caption))
        .tag(2)
}

Screenshot

Group

Group creates several views to act as one, also to avoid Stack’s 10 View maximum limit.

VStack {
    Group {
        Text("Hello")
        Text("Hello")
        Text("Hello")
    }
    Group {
        Text("Hello")
        Text("Hello")
    }
}

Screenshot

Alerts and Action Sheets

To Show an Alert

Alert(
    title: Text("Title"), 
    message: Text("message"), 
    dismissButton: .default(Text("Ok!"))
)

To Show Action Sheet

ActionSheet(
    title: Text("Title"), 
    message: Text("Message"), 
    buttons: [
        .default(Text("Ok!"), action: { print("hello") })
    ]
)

Navigation

Navigate via NavigationLink

NavigationView {
    NavigationLink(destination: SecondView()) {
        Text("Show")
    }.navigationBarTitle(Text("First View"))
}

Screenshot

Navigate via tap on List Item

let names = ["Thanos", "Iron man", "Ant man"]
List(names, id: \.self) { name in
    NavigationLink(destination: HeroView(name: name)) {
        Text(name)
    }
}

Work with UIKit

Navigate to ViewController

It’s possible to work with UIKit components from SwiftUI or call SwiftUI views as View Controllers from UIKit.

Let’s say you have a View Controller named SuperVillainViewController and want to call it from a SwiftUI view, to do that ViewController needs to implement UIViewControllerRepresentable:

struct SuperVillainViewController: UIViewControllerRepresentable {
    var controllers: [UIViewController]
    func makeUIViewcontroller(context: Context) -> SuperVillainViewController {
        // you could have a custom constructor here, I'm just keeping it simple
        let vc = SuperVillainViewController()
        return vc
    }
}

Now you can use it like

NavigationLink(destination: SuperVillainViewController()) {
    Text("Click")
}

Use UIKit and SwiftUI Views Together

To use UIView subclasses from within SwiftUI, you wrap the other view in a SwiftUI view that conforms to the UIViewRepresentable protocol. (Reference)

as example

import SwiftUI
import MapKit

struct MapView: UIViewRepresentable {
    func makeUIView(context: Context) -> MKMapView {
        MKMapView(frame: .zero)
    }

    func updateUIView(_ view: MKMapView, context: Context) {
        let coordinate = CLLocationCoordinate2D(
            latitude: 34.011286, 
            longitude: -116.166868
        )
        let span = MKCoordinateSpan(latitudeDelta: 2.0, longitudeDelta: 2.0)
        let region = MKCoordinateRegion(center: coordinate, span: span)
        view.setRegion(region, animated: true)
    }
}

struct MapView_Preview: PreviewProvider {
    static var previews: some View {
        MapView()
    }
}

Resource

UIKit equivalent in SwiftUI

View

Text

Label

TextEditor

Map

Image

Shape

ProgressView

Layout

Background

VStack

HStack

ZStack

LazyVStack

LazyHStack

LazyVGrid

LazyHGrid

Input

Toggle

Button

TextField

Slider

Date Picker

Picker

Stepper

Tap

Gesture

OnChange

List

Containers

NavigationView

TabView

Group

Alerts and Action Sheets

Navigation

Work with UIKit

Navigate to ViewController

Use UIKit and SwiftUI Views Together

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