This Article Covers Following Related questions  :

How to Switch Between List View and Grid View in iOS.
UICollectionView - ListView and GridView.
Change the flow layout of a collectionView – from grid to list view.
Converting a UICollectionView to a UITableView.
Swift ios switching between listview and gridview
uitableview uicollectionview switch
uicollectionview table layout

Getting Started :

Creating ListCell :

class ListCell : UICollectionViewCell {
    override init(frame: CGRect) {
        super.init(frame: frame)
        setUpViews()
    }
    
    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}

let imgView : UIImageView = {
    let imageView = UIImageView()
    imageView.image = UIImage(named: "car.jpg")
    imageView.contentMode = .scaleAspectFill
    imageView.clipsToBounds = true
    imageView.translatesAutoresizingMaskIntoConstraints = false
    return imageView
}()

let titleLabel : UILabel = {
    let label = UILabel()
    label.translatesAutoresizingMaskIntoConstraints = false
    label.font = UIFont.preferredFont(forTextStyle: UIFontTextStyle.title2)
    
    return label
}()

let descriptionLabel : UILabel = {
    let label = UILabel()
    label.translatesAutoresizingMaskIntoConstraints = false
    label.numberOfLines = 0
    label.font = UIFont.preferredFont(forTextStyle: UIFontTextStyle.body)
    return label
}()

func setUpViews() {
    backgroundColor = UIColor.init(red: 245.0/255.0, green: 245.0/255.0, blue: 245.0/255.0, alpha: 1.0)
    addSubview(imgView)
    addSubview(titleLabel)
    addSubview(descriptionLabel)
    imgView.leadingAnchor.constraint(equalTo: leadingAnchor, constant: 0).isActive = true
    imgView.bottomAnchor.constraint(equalTo: bottomAnchor, constant: 0).isActive = true
    imgView.topAnchor.constraint(equalTo: topAnchor, constant: 0).isActive = true
    imgView.widthAnchor.constraint(equalToConstant: frame.height).isActive = true
    
    titleLabel.leadingAnchor.constraint(equalTo: imgView.trailingAnchor, constant: 8).isActive = true
    titleLabel.topAnchor.constraint(equalTo: imgView.topAnchor, constant: 4).isActive = true
    titleLabel.setContentCompressionResistancePriority(.defaultHigh, for: .vertical)
    
    descriptionLabel.topAnchor.constraint(equalTo: titleLabel.bottomAnchor, constant: 4).isActive = true
    descriptionLabel.leadingAnchor.constraint(equalTo: imgView.trailingAnchor, constant: 8).isActive = true
    descriptionLabel.bottomAnchor.constraint(equalTo: imgView.bottomAnchor, constant: -4).isActive = true
    descriptionLabel.trailingAnchor.constraint(equalTo: trailingAnchor, constant: -8).isActive = true
    descriptionLabel.setContentCompressionResistancePriority(.defaultLow, for: .vertical)
}

let listCellIdentifier = "ListCell"

var isListView = false

var toggleButton = UIBarButtonItem()

collectionView?.register(ListCell.self, forCellWithReuseIdentifier: listCellIdentifier)

toggleButton = UIBarButtonItem(title: "List", style: .plain, target: self, action: #selector(butonTapped(sender:)))
self.navigationItem.setRightBarButton(toggleButton, animated: true)

@objc func butonTapped(sender: UIBarButtonItem) {
    if isListView {
        toggleButton = UIBarButtonItem(title: "List", style: .plain, target: self, action: #selector(butonTapped(sender:)))
        isListView = false
    }else {
        toggleButton = UIBarButtonItem(title: "Grid", style: .plain, target: self, action: #selector(butonTapped(sender:)))
        isListView = true
    }
    self.navigationItem.setRightBarButton(toggleButton, animated: true)
    self.collectionView?.reloadData()
}

if isListView {
    let cell = collectionView.dequeueReusableCell(withReuseIdentifier: listCellIdentifier, for: indexPath) as! ListCell
    cell.titleLabel.text = "Ferrari 812 Superfast"
    cell.descriptionLabel.text = "The car has a larger 6.5-liter V12 engine compared to the 6.3-liter used in the F12berlinetta. The engine produces 800 PS (588 kW, 789 bhp) at 8,500 rpm and 718 N·m (530 lbf·ft) of torque at 7,000 rpm. The 812 Superfast's V12 engine is, in 2017, the most powerful naturally aspirated production car engine ever made."
    return cell
}else {
    let cell = collectionView.dequeueReusableCell(withReuseIdentifier: cellIdentifier, for: indexPath) as! CustomCell
    return cell
}

let width = view.frame.width
if isListView {
    return CGSize(width: width, height: 120)
}else {
    return CGSize(width: (width - 15)/2, height: (width - 15)/2)
}

Requirements : 

Getting Started :

import ARKit

var sceneView = ARSCNView()

sceneView.frame = view.frame
view.addSubview(sceneView)

let configuration = ARWorldTrackingSessionConfiguration()

sceneView.session.run(configuration)

@IBAction func addCubeButtonTapped(sender: UIButton) {
    print("Cube Button Tapped")
}

func addButton() {
    let button = UIButton()
    view.addSubview(button)
    button.translatesAutoresizingMaskIntoConstraints = false
    button.setTitle("Add a CUBE", for: .normal)
    button.setTitleColor(UIColor.red, for: .normal)
    button.backgroundColor = UIColor.white.withAlphaComponent(0.4)
    button.addTarget(self, action: #selector(addCubeButtonTapped(sender:)) , for: .touchUpInside)
    
    // Contraints
    button.bottomAnchor.constraint(equalTo: view.bottomAnchor, constant: -8.0).isActive = true
    button.centerXAnchor.constraint(equalTo: view.centerXAnchor, constant: 0.0).isActive = true
    button.heightAnchor.constraint(equalToConstant: 50)
}

let cubeNode = SCNNode(geometry: SCNBox(width: 0.1, height: 0.1, length: 0.1, chamferRadius: 0)) // SceneKit/AR coordinates are in meters

cubeNode.position = SCNVector3(0, 0, -0.2)

self.sceneView.scene.rootNode.addChildNode(cubeNode)

func getMyCameraCoordinates(sceneView: ARSCNView) -> MDLTransform {
    let cameraTransform = sceneView.session.currentFrame?.camera.transform
    let cameraCoordinates = MDLTransform(matrix: cameraTransform!)
    return cameraCoordinates
}

DispatchQueue.main.async {
    print("cube button tapped")
    let cubeNode = SCNNode(geometry: SCNBox(width: 0.1, height: 0.1, length: 0.1, chamferRadius: 0))
    let cc = self.getMyCameraCoordinates(sceneView: self.sceneView)
    cubeNode.position = SCNVector3(cc.translation.x, cc.translation.y, cc.translation.z)
    self.sceneView.scene.rootNode.addChildNode(cubeNode)
}

This Article Covers Following Related questions  :

 

1. Email Validation :

Some valid emails :

func isValidEmail(email: String) -> Bool {
    let emailRegEx = "[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,4}"
    let emailTest = NSPredicate(format:"SELF MATCHES %@", emailRegEx)
    let result = emailTest.evaluate(with: email)
    return result
}

var isValid = isValidEmail(email: textField.text!)

2. Password Validation :

Some valid Password :

func isValidPassword(password: String) -> Bool {
    let passwordRegEx = "^(?=.*[a-z])(?=.*[$@$#!%*?&])[A-Za-z\\d$@$#!%*?&]{6,16}"
    let passwordTest = NSPredicate(format:"SELF MATCHES %@", passwordRegEx)
    let result = passwordTest.evaluate(with: password)
    return result
}

var isValid = isValidPassword(email: textField.text!)

3. URL Validation :

Some valid Url's :

func isValidUrl(url: String) -> Bool {
    let urlRegEx = "(http|https)://((\\w)*|([0-9]*)|([-|_])*)+([\\.|/]((\\w)*|([0-9]*)|([-|_])*))+"
    let urlTest = NSPredicate(format:"SELF MATCHES %@", urlRegEx)
    let result = urlTest.evaluate(with: url)
    return result
}

var isValid = isValidUrl(email: textField.text!)

This Article Covers All Related questions  :

UICollectionView :

Sample Project :

window = UIWindow(frame: UIScreen.main.bounds) // 1
window?.makeKeyAndVisible()
let layout = UICollectionViewFlowLayout() // 2
let viewController = ViewController(collectionViewLayout: layout) // 3
window?.rootViewController = UINavigationController(rootViewController: viewController) // 4

Creating Custom CollectionViewCell:

class CustomCell: UICollectionViewCell{
    
}

override init(frame: CGRect) {
    super.init(frame: frame)
}

required init?(coder aDecoder: NSCoder) {
    fatalError("init(coder:) has not been implemented")
}

let imgView : UIImageView = {
    let imageView = UIImageView()
    imageView.translatesAutoresizingMaskIntoConstraints = false
    imageView.image = UIImage(named: "car.png")
    imageView.contentMode = .scaleAspectFill
    return imageView
}()

addSubview(imgView)
imgView.leadingAnchor.constraint(equalTo: leadingAnchor).isActive = true
imgView.trailingAnchor.constraint(equalTo: trailingAnchor).isActive = true
imgView.topAnchor.constraint(equalTo: topAnchor).isActive = true
imgView.bottomAnchor.constraint(equalTo: bottomAnchor).isActive = true

Add Custom cell to Collection View :

let cellIdentifier = "ImageCell"

collectionView?.backgroundColor = UIColor.white
collectionView?.register(CustomCell.self, forCellWithReuseIdentifier: cellIdentifier)

override func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
    return 6
}

override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
    
    let cell = collectionView.dequeueReusableCell(withReuseIdentifier: cellIdentifier, for: indexPath) as! CustomCell
    
    return cell
}

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
    let width = view.frame.width
    return CGSize(width: (width - 15)/2, height: (width - 15)/2)
}

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumLineSpacingForSectionAt section: Int) -> CGFloat {
    return 5
}

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumInteritemSpacingForSectionAt section: Int) -> CGFloat {
    return 5
}

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, insetForSectionAt section: Int) -> UIEdgeInsets {
    return UIEdgeInsets(top: 5, left: 5, bottom: 5, right: 5)
}

This Article Covers All Related questions  :

UserNotifications :

Local Notification :

When to Use :

Example Project:

func addingButton() {
    let sendButton = UIButton()
    view.addSubview(sendButton)
    sendButton.translatesAutoresizingMaskIntoConstraints = false
    sendButton.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
    sendButton.centerYAnchor.constraint(equalTo: view.centerYAnchor).isActive = true
    sendButton.widthAnchor.constraint(equalToConstant: 200).isActive = true
    sendButton.heightAnchor.constraint(equalToConstant: 50).isActive = true
    sendButton.setTitle("Send Notification", for: .normal)
    sendButton.setTitleColor(UIColor.white, for: .normal)
    sendButton.backgroundColor = UIColor.blue
    
    sendButton.addTarget(self, action: #selector(buttonTapped(sender:)), for: .touchUpInside)
}

@objc func buttonTapped(sender: UIButton) {

}

RequestAuthorization :

override func viewDidLoad() {
    super.viewDidLoad()
    addingButton()
    let center = UNUserNotificationCenter.current()
    center.requestAuthorization(options: [.alert, .sound]) { (granted, error) in
        if (granted) {
            print("granted")
        }else {
            print(error?.localizedDescription as Any)
        }
    }
}

Send Notification with Content :

let content = UNMutableNotificationContent()
content.title = NSString.localizedUserNotificationString(forKey: "Good morning!", arguments: nil)
content.body = NSString.localizedUserNotificationString(forKey: "Wake up! It's morning time!",
                                                        arguments: nil)
content.sound = UNNotificationSound.default()

let trigger = UNTimeIntervalNotificationTrigger(timeInterval:TimeInterval(10)  , repeats: false)

let request = UNNotificationRequest(identifier: "MorningAlarm", content: content, trigger: trigger)

let center = UNUserNotificationCenter.current()
center.add(request) { (error : Error?) in
    if let theError = error {
        print(theError.localizedDescription)
    }
}

UNUserNotificationCenterDelegate :

center.delegate = self

Foreground :

func userNotificationCenter(_ center: UNUserNotificationCenter,
                            willPresent notification: UNNotification,
                            withCompletionHandler completionHandler: @escaping (UNNotificationPresentationOptions) -> Void) {
    print(notification.request.content.title)
    
    // Play a sound.
    completionHandler(UNNotificationPresentationOptions.sound)
}

Background :

func userNotificationCenter(_ center: UNUserNotificationCenter,
                            didReceive response: UNNotificationResponse,
                            withCompletionHandler completionHandler: @escaping () -> Void) {
    print(response.notification.request.content.title)
    
}

This Article Covers All Related questions  :

Add UITextField :

var textField = UITextField()

func addTextField() {
    view.addSubview(textField)
    textField.translatesAutoresizingMaskIntoConstraints = false
    textField.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: 40.0).isActive = true
    textField.trailingAnchor.constraint(equalTo: view.trailingAnchor, constant: -40.0).isActive = true
    textField.topAnchor.constraint(equalTo: view.topAnchor, constant: 40.0).isActive = true
    textField.placeholder = "Select date"
    textField.borderStyle = .roundedRect
}

Add UIDatePicker As Keyboard :

var textField = UITextField()
var datePicker = UIDatePicker()

func createDatePicker() {
    datePicker.datePickerMode = .date
    datePicker.addTarget(self, action: #selector(self.datePickerValueChanged(datePicker:)), for: .valueChanged)
}

@objc func datePickerValueChanged(datePicker: UIDatePicker) {
    
}

textField.inputView = datePicker

let dateFormatter = DateFormatter()
dateFormatter.dateStyle = .medium
dateFormatter.timeStyle = .none

textField.text = dateFormatter.string(from: datePicker.date)

Add UIToolBar To UIDatePicker :

var textField = UITextField()
var datePicker = UIDatePicker()
var toolBar = UIToolbar()

func createToolBar() {
    toolBar = UIToolbar(frame: CGRect(x: 0, y: 0, width: view.frame.width, height: 40))
    
    let todayButton = UIBarButtonItem(title: "Today", style: .plain, target: self, action: #selector(todayButtonPressed(sender:)))
    
    let doneButton = UIBarButtonItem(barButtonSystemItem: .done, target: self, action: #selector(doneButtonPressed(sender:)))
    
    let label = UILabel(frame: CGRect(x: 0, y: 0, width: view.frame.width/3, height: 40))
    label.text = "Choose your Date"
    let labelButton = UIBarButtonItem(customView:label)
    
    let flexibleSpace = UIBarButtonItem(barButtonSystemItem: .flexibleSpace, target: self, action: nil)
    
    toolBar.setItems([todayButton,flexibleSpace,labelButton,flexibleSpace,doneButton], animated: true)
}

todayButton:

@objc func todayButtonPressed(sender: UIBarButtonItem) {
    let dateFormatter = DateFormatter() // 1
    dateFormatter.dateStyle = .medium
    dateFormatter.timeStyle = .none
    
    textField.text = dateFormatter.string(from: Date()) // 2
    
    textField.resignFirstResponder()
}

doneButton :

@objc func doneButtonPressed(sender: UIBarButtonItem) {
    textField.resignFirstResponder()
}

labelButton :

flexibleSpace :

textField.inputAccessoryView = toolBar