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SwiftUI Cheat Sheet
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README.md

SwiftUI Cheat Sheet

SwiftUI

Table of Contents

Resource

UIKit equivalent in SwiftUI

UIKit SwiftUI
UILabel Text
UIImageView Image
UITextField TextField
UITextView No equivalent (use Text)
UISwitch Toggle
UISlider Slider
UIButton Button
UITableView List
UICollectionView No equivalent (can be implemented by List)
UINavigationController NavigationView
UIAlertController with style .alert Alert
UIAlertController with style .actionSheet ActionSheet
UIStackView with horizontal axis HStack
UIStackView with vertical axis VStack
UISegmentedControl SegmentedControl
UIStepper Stepper
UIDatePicker DatePicker
NSAttributedString No equivalent (use Text)

View

Text

To show a text in UI simply write

Text("Hello World")

To add style

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

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)")
}

Image

To show image

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

To use system icon

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

you can add style to system icon set

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

Add style to Image

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

Shape

To create Rectangle

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

To create circle

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

Layout

Background

To use image as a background

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

Gradient background

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

VStack

Shows child view vertically

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

Styling

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

HStack

Shows child view horizontally

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

ZStack

To create overlapping content use ZStack

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

Input

Toggle

Toggle lets users move between true and false states

@State var isShowing = true //state

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

Button

To create button

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

To create image Button

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

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

To create secure TextField

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

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

Slider

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

Date Picker

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

Segmented Control

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

SegmentedControl(selection: $favoriteColor) {
    ForEach(0..<colors.count) { index in
        Text(self.colors[index]).tag(index)
    }
}

Stepper

@State var count:Int = 0

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

or

@State var count:Int = 0

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

Tap

For single tap

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

For double tap

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

Gesture

Gesture like TapGesture, LongPressGesture, DragGesture

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

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

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

List

To create static scrollable List

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

To create dynamic List

let names = ["Thanos", "Iron man", "Ant man"]
List(names) { name in
        Text(name)
}

To add section

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

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

To make it grouped add .listStyle(.grouped)

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

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

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)
}

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")
                }) {
                    Text("Setting")
                })
}

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")
    }
}

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!"), onTrigger: {
    print("hello")
})])

Navigation

Navigate via NavigationButton

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

Navigate via tap on List Item

let names = ["Thanos", "Iron man", "Ant man"]
List(names) { name in
    NavigationButton(destination: HeroView(name: name)) {
        Text(name)
    }
}

Navigate via PresentationButton

PresentationButton(Text("Tap"), destination: HeroView())

Work with UIKIT

Navigate to ViewController

It's possible to work with UIKIT component from SwiftUI or call SwiftUI view as View Controller from UIKIT.

Let's say you have a View Controller named as SuperVillainViewController and want to call from SwiftUI view, to do that ViewController need 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

NavigationButton(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()
    }
}
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