Swift 5 Code snippets

Add leading padding to view added inside an UIStackView

stackView.layoutMargins = UIEdgeInsets(top: 0, left: 20, bottom: 0, right: 20)
stackView.isLayoutMarginsRelativeArrangement = true

https://stackoverflow.com/questions/32551890/how-to-add-leading-padding-to-view-added-inside-an-uistackview

Timestamp

// current date and time
let someDate = Date()

// time interval since 1970
let myTimeStamp = someDate.timeIntervalSince1970

Change year in Date

var component = calendar.dateComponents([.year, .month, .day, .hour, .minute, .second], from: base)
component.year = year
Calendar.current.date(from: component)

https://dev.to/onmyway133/changing-year-in-date-in-swift

Date tomorrow

extension Date {
    static var yesterday: Date { return Date().dayBefore }
    static var tomorrow:  Date { return Date().dayAfter }
    var dayBefore: Date {
        return Calendar.current.date(byAdding: .day, value: -1, to: noon)!
    }
    var dayAfter: Date {
        return Calendar.current.date(byAdding: .day, value: 1, to: noon)!
    }
    var noon: Date {
        return Calendar.current.date(bySettingHour: 12, minute: 0, second: 0, of: self)!
    }
    var month: Int {
        return Calendar.current.component(.month,  from: self)
    }
    var isLastDayOfMonth: Bool {
        return dayAfter.month != month
    }
}

https://stackoverflow.com/a/44009988

iOS local notification

// Notification center property
let userNotificationCenter = UNUserNotificationCenter.current()

func requestNotificationAuthorization() {
    let authOptions = UNAuthorizationOptions.init(arrayLiteral: .alert, .badge, .sound)
    
    self.userNotificationCenter.requestAuthorization(options: authOptions) { (success, error) in
        if let error = error {
            print("Error: ", error)
        }
    }
}

override func viewDidLoad() {
    super.viewDidLoad()
    self.requestNotificationAuthorization()
    self.sendNotification()
}

func sendNotification() {
    let notificationContent = UNMutableNotificationContent()
    notificationContent.title = "Test"
    notificationContent.body = "Test body"
    notificationContent.badge = NSNumber(value: 3)
    
    if let url = Bundle.main.url(forResource: "dune",
                                withExtension: "png") {
        if let attachment = try? UNNotificationAttachment(identifier: "dune",
                                                        url: url,
                                                        options: nil) {
            notificationContent.attachments = [attachment]
        }
    }
    
    let trigger = UNTimeIntervalNotificationTrigger(timeInterval: 5,
                                                    repeats: false)
    let request = UNNotificationRequest(identifier: "testNotification",
                                        content: notificationContent,
                                        trigger: trigger)
    
    userNotificationCenter.add(request) { (error) in
        if let error = error {
            print("Notification Error: ", error)
        }
    }
}

// Local notifications
func application(_ application: UIApplication, didReceive notification: UILocalNotification) {
    UIApplication.shared.applicationIconBadgeNumber = 0
}

// Assing self delegate on userNotificationCenter
self.userNotificationCenter.delegate = self

func userNotificationCenter(_ center: UNUserNotificationCenter, didReceive response: UNNotificationResponse, withCompletionHandler completionHandler: @escaping () -> Void) {
    completionHandler()
}

func userNotificationCenter(_ center: UNUserNotificationCenter, willPresent notification: UNNotification, withCompletionHandler completionHandler: @escaping (UNNotificationPresentationOptions) -> Void) {
    completionHandler([.alert, .badge, .sound])
}

https://programmingwithswift.com/how-to-send-local-notification-with-swift-5/

Get bandle file path

let dbUrl = Bundle.main.url(forResource: "myDb", withExtension: "db")!
let dbPath = dbUrl.path

Mark

// MARK: A mark comment lives here.

// MARK: - A mark comment lives here. A separation line is added.

// MARK: -

https://stackoverflow.com/a/35963262

Save photo to album

UIImageWriteToSavedPhotosAlbum(yourImage, self, #selector(image(_:didFinishSavingWithError:contextInfo:)), nil)


@objc func image(_ image: UIImage, didFinishSavingWithError error: NSError?, contextInfo: UnsafeRawPointer) {
    if let error = error {
        // we got back an error!
        let ac = UIAlertController(title: "Save error", message: error.localizedDescription, preferredStyle: .alert)
        ac.addAction(UIAlertAction(title: "OK", style: .default))
        present(ac, animated: true)
    } else {
        let ac = UIAlertController(title: "Saved!", message: "Your altered image has been saved to your photos.", preferredStyle: .alert)
        ac.addAction(UIAlertAction(title: "OK", style: .default))
        present(ac, animated: true)
    }
}

https://www.hackingwithswift.com/example-code/media/uiimagewritetosavedphotosalbum-how-to-write-to-the-ios-photo-album

Copy text to the clipboard

let pasteboard = UIPasteboard.general
pasteboard.string = "Hello, world!"

if let string = pasteboard.string {
    // text was found and placed in the "string" constant
}

https://www.hackingwithswift.com/example-code/system/how-to-copy-text-to-the-clipboard-using-uipasteboard

Get configuration from PLIST

// Environment.swift

import Foundation

public enum Environment {
  // MARK: - Keys
  enum Keys {
    enum Plist {
      static let rootURL = "ROOT_URL"
      static let apiKey = "API_KEY"
    }
  }

  // MARK: - Plist
  private static let infoDictionary: [String: Any] = {
    guard let dict = Bundle.main.infoDictionary else {
      fatalError("Plist file not found")
    }
    return dict
  }()

  // MARK: - Plist values
  static let rootURL: URL = {
    guard let rootURLstring = Environment.infoDictionary[Keys.Plist.rootURL] as? String else {
      fatalError("Root URL not set in plist for this environment")
    }
    guard let url = URL(string: rootURLstring) else {
      fatalError("Root URL is invalid")
    }
    return url
  }()

  static let apiKey: String = {
    guard let apiKey = Environment.infoDictionary[Keys.Plist.apiKey] as? String else {
      fatalError("API Key not set in plist for this environment")
    }
    return apiKey
  }()
}

https://thoughtbot.com/blog/let-s-setup-your-ios-environments

WatchOS update complications

        let server = CLKComplicationServer.sharedInstance()
        for complication in server.activeComplications ?? [] {
                server.reloadTimeline(for: complication)

        }

SFSafariViewController reader mode

let urlString = "http://www.google.com"
let url = URL(string: urlString)!
let config = SFSafariViewController.Configuration()
config.entersReaderIfAvailable = true
let safariVC = SFSafariViewController(url: url, configuration: config)
present(safariVC, animated: true, completion: nil)

https://stackoverflow.com/a/49107463

Change default global tint color

@UIApplicationMain class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?

    func application(application: UIApplication!, didFinishLaunchingWithOptions launchOptions: NSDictionary!) -> Bool {

        self.window = UIWindow(frame: UIScreen.mainScreen().bounds)

        // ...

        self.window!.tintColor = UIColor.orangeColor()

        return true
    }
}

https://stackoverflow.com/a/25095089

simulator sqlite db paths

let dirPaths = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true)
var docsDir = dirPaths[0]

print(docsDir)

// use app grpup

public lazy var applicationDocumentsDirectory: URL? = {
        // The directory the applicatio:  uses to store the Core Data store file. This code uses a directory named "com.nootapp.CoreDataTest" in the application's documents Application Support directory
        return FileManager.default.containerURL(forSecurityApplicationGroupIdentifier: "group.com.appgroup")
}()

guard let storeURL = self.applicationDocumentsDirectory?.appendingPathComponent("CoreData.sqlite") else {
            fatalError("Could not get sqlite url.")
        }

Swift.debugPrint("storeURL", storeURL.absoluteString)

check iCloud login

if FileManager.default.ubiquityIdentityToken != nil {
    print("iCloud Available")
} else {
    print("iCloud Unavailable")
}

https://stackoverflow.com/a/39053572

display base64 string image

if let imageData = Data.init(base64Encoded: base64String) {
imageView.image = UIImage(data: imageData)
}

SF symbols

https://www.avanderlee.com/swift/sf-symbols-guide/

hide files

extension URL {
    /// `true` is hidden (invisible) or `false` is not hidden (visible)
    var isHidden: Bool {
        get {
            return (try? resourceValues(forKeys: [.isHiddenKey]))?.isHidden == true
        }
        set {
            var resourceValues = URLResourceValues()
            resourceValues.isHidden = newValue
            do {
                try setResourceValues(resourceValues)
            } catch {
                print("isHidden error:", error)
            }
        }
    }
}

https://stackoverflow.com/a/34746109

App and build version

// app version
if let appVersion = Bundle.main.infoDictionary?["CFBundleShortVersionString"] as? String {
      // present appVersion
}

if let buildVersion = Bundle.main.infoDictionary?["CFBundleVersion"] as? String {
      // present buildVersion
 }

https://stackoverflow.com/a/59350389

Providing Access to Directories

swiftlint script

if which swiftlint >/dev/null; then
  swiftlint autocorrect
  swiftlint
else
  echo "warning: SwiftLint not installed, download from https://github.com/realm/SwiftLint"
fi

https://stackoverflow.com/a/57051011

Using KVO to listen to volume changes

class YourViewController: UIViewController {

    var obs: NSKeyValueObservation?

    override func viewDidLoad() {
        super.viewDidLoad()

        let audioSession = AVAudioSession.sharedInstance()
        self.obs = audioSession.observe( \.outputVolume ) { (av, change) in
            print("volume \(av.outputVolume)")
        }
    }
}

https://stackoverflow.com/a/51437265 https://www.ralfebert.de/ios-examples/swift/property-key-value-observer/

Find list of Local Notification the app has already set

let center = UNUserNotificationCenter.current()

override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(animated)

    center.getPendingNotificationRequests { (notifications) in
        print("Count: \(notifications.count)")
        for item in notifications {
          print(item.content)
        }
    }
}

https://stackoverflow.com/a/39034576

Check if remote push notifications are enabled

let current = UNUserNotificationCenter.current()

current.getNotificationSettings(completionHandler: { (settings) in
    if settings.authorizationStatus == .notDetermined {
        // Notification permission has not been asked yet, go for it!
    } else if settings.authorizationStatus == .denied {
        // Notification permission was previously denied, go to settings & privacy to re-enable
    } else if settings.authorizationStatus == .authorized {
        // Notification permission was already granted
    }
})

https://stackoverflow.com/a/44407514

Change the color of a link in an NSMutableAttributedString

The link color is the tint color of the label/textView. So, you can change it by changing the tint color of the view. However, this will not work if you want different link colours within the same view.

https://stackoverflow.com/a/33431102

Present ViewController in full screen

let detailVC = DetailViewController()
detailVC.modalPresentationStyle = .fullScreen
present(detailVC, animated: true)

objective-c code call swift extension

extension UIColor {

    // As of Swift 4.0.3, the @objc annotation is needed if you want to use the extension in Objective-C files
    @objc
    class func otherEventColor() -> UIColor {
        return UIColor(red:0.525, green:0.49, blue:0.929, alpha:1)
    }
}

Then `#import "ProductModuleName-Swift.h"1 in your ObjC file.

https://stackoverflow.com/a/32275959

Delete all Core Data records of an entity

func deleteAllRecords() {
    let delegate = UIApplication.shared.delegate as! AppDelegate
    let context = delegate.persistentContainer.viewContext

    let deleteFetch = NSFetchRequest<NSFetchRequestResult>(entityName: "CurrentCourse")
    let deleteRequest = NSBatchDeleteRequest(fetchRequest: deleteFetch)

    do {
        try context.execute(deleteRequest)
        try context.save()
    } catch {
        print ("There was an error")
    }
}

https://stackoverflow.com/a/43129221

Notification send an object

func post() {
    NotificationCenter.default.post(name: Notification.Name("SomeNotificationName"),
        object: nil, 
        userInfo:["key0": "value", "key1": 1234])
}

func addObservers() {
    NotificationCenter.default.addObserver(self, 
        selector: #selector(someMethod), 
        name: Notification.Name("SomeNotificationName"), 
        object: nil)
}

@objc func someMethod(_ notification: Notification) {
    let info0 = notification.userInfo?["key0"]
    let info1 = notification.userInfo?["key1"]
}

https://stackoverflow.com/a/41366080

thread-safe access

let queue = DispatchQueue(label: "thread-safe-obj", attributes: .concurrent)

// write
queue.async(flags: .barrier) {
    // perform writes on data
}

// read
var value: ValueType!
queue.sync {
    // perform read and assign value
}
return value

https://stackoverflow.com/a/28976644

Use `UIActivityIndicatorView`

class SpinnerViewController: UIViewController {
    var spinner = UIActivityIndicatorView(style: .whiteLarge)

    override func loadView() {
        view = UIView()
        view.backgroundColor = UIColor(white: 0, alpha: 0.7)

        spinner.translatesAutoresizingMaskIntoConstraints = false
        spinner.startAnimating()
        view.addSubview(spinner)

        spinner.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
        spinner.centerYAnchor.constraint(equalTo: view.centerYAnchor).isActive = true
    }
}

func createSpinnerView() {
    let child = SpinnerViewController()

    // add the spinner view controller
    addChild(child)
    child.view.frame = view.frame
    view.addSubview(child.view)
    child.didMove(toParent: self)

    // wait two seconds to simulate some work happening
    DispatchQueue.main.asyncAfter(deadline: .now() + 2) {
        // then remove the spinner view controller
        child.willMove(toParent: nil)
        child.view.removeFromSuperview()
        child.removeFromParent()
    }
}

https://www.hackingwithswift.com/example-code/uikit/how-to-use-uiactivityindicatorview-to-show-a-spinner-when-work-is-happening

Swift queue

class Queue<T> {
  private var elements: [T] = []

  func enqueue(_ value: T) {
    elements.append(value)
  }

  func dequeue() -> T? {
    guard !elements.isEmpty else {
      return nil
    }
    return elements.removeFirst()
  }

  var head: T? {
    return elements.first
  }

  var tail: T? {
    return elements.last
  }
}

https://benoitpasquier.com/data-structure-implement-queue-swift/

`URLQueryItem`

import Foundation
import XCPlayground

let queryItems = [URLQueryItem(name: "id", value: "1"), URLQueryItem(name: "id", value: "2")]
var urlComps = URLComponents(string: "www.apple.com/help")!
urlComps.queryItems = queryItems
let result = urlComps.url!
print(result)

`Operation` and `Operation Queue`

https://www.raywenderlich.com/5293-operation-and-operationqueue-tutorial-in-swift

Send email, sms and phone call

    func sendEmail(email: String) {
        if MFMailComposeViewController.canSendMail() {
            let mail = MFMailComposeViewController()
            mail.mailComposeDelegate = self
            mail.setToRecipients([email])

            present(mail, animated: true)
        } else {

        }
    }

//MFMailComposeViewControllerDelegate
    func mailComposeController(_ controller: MFMailComposeViewController, didFinishWith result: MFMailComposeResult, error: Error?) {
        controller.dismiss(animated: true)
    }

    func sendSMS(with phoneNumber: String) {
        if MFMessageComposeViewController.canSendText() {
            let messageComposeViewController = MFMessageComposeViewController()
            messageComposeViewController.messageComposeDelegate = self
            messageComposeViewController.recipients = [phoneNumber]
            self.present(messageComposeViewController, animated: true, completion: nil)
        }
    }

// MFMessageComposeViewControllerDelegate
     func messageComposeViewController(_ controller: MFMessageComposeViewController, didFinishWith result: MessageComposeResult) {
        controller.dismiss(animated: true)
    }

    func callNumber(phoneNumber: String) {
        if let url = URL(string: "tel://\(phoneNumber)"), UIApplication.shared.canOpenURL(url) {
            if #available(iOS 10, *) {
                UIApplication.shared.open(url)
            } else {
                UIApplication.shared.openURL(url)
            }
        }
    }

Set the maximum character length of a UITextField

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    let maxLength = 1
    let currentString: NSString = (textField.text ?? "") as NSString
    let newString: NSString =
        currentString.replacingCharacters(in: range, with: string) as NSString
    return newString.length <= maxLength
}

https://stackoverflow.com/a/31363255

Present view controller push animation

extension UIViewController {

    func presentDetail(_ viewControllerToPresent: UIViewController) {
        let transition = CATransition()
        transition.duration = 0.25
        transition.type = CATransitionType.push
        transition.subtype = CATransitionSubtype.fromRight
        self.view.window?.layer.add(transition, forKey: kCATransition)

        present(viewControllerToPresent, animated: false)
    }

    func dismissDetail() {
        let transition = CATransition()
        transition.duration = 0.25
        transition.type = CATransitionType.push
        transition.subtype = CATransitionSubtype.fromLeft
        self.view.window?.layer.add(transition, forKey: kCATransition)

        dismiss(animated: false)
    }
}

https://stackoverflow.com/a/42627260

floating button

import UIKit

extension UIViewController {
    private struct AssociatedKeys {
        static var floatingButton: UIButton?
    }

    var floatingButton: UIButton? {
        get {
            guard let value = objc_getAssociatedObject(self, &AssociatedKeys.floatingButton) as? UIButton else {return nil}
            return value
        }
        set(newValue) {
            objc_setAssociatedObject(self, &AssociatedKeys.floatingButton, newValue, .OBJC_ASSOCIATION_RETAIN_NONATOMIC)
        }
    }

    func addFloatingButton() {
        // Customize your own floating button UI
        let button = UIButton(type: .custom)
        let image = UIImage(named: "tab_livesupport_unselected")?.withRenderingMode(.alwaysTemplate)
        button.tintColor = .white
        button.setImage(image, for: .normal)
        button.backgroundColor = UIColor.obiletGreen
        button.layer.shadowColor = UIColor.black.cgColor
        button.layer.shadowRadius = 3
        button.layer.shadowOpacity = 0.12
        button.layer.shadowOffset = CGSize(width: 0, height: 1)
        button.sizeToFit()
        let buttonSize = CGSize(width: 60, height: 60)
        let rect = UIScreen.main.bounds.insetBy(dx: 4 + buttonSize.width / 2, dy: 4 + buttonSize.height / 2)
        button.frame = CGRect(origin: CGPoint(x: rect.maxX - 15, y: rect.maxY - 50), size: CGSize(width: 60, height: 60))
        // button.cornerRadius = 30 -> Will destroy your shadows, however you can still find workarounds for rounded shadow.
        button.autoresizingMask = []
        view.addSubview(button)
        floatingButton = button
        let panner = UIPanGestureRecognizer(target: self, action: #selector(panDidFire(panner:)))
        floatingButton?.addGestureRecognizer(panner)
        snapButtonToSocket()
    }

    @objc fileprivate func panDidFire(panner: UIPanGestureRecognizer) {
        guard let floatingButton = floatingButton else {return}
        let offset = panner.translation(in: view)
        panner.setTranslation(CGPoint.zero, in: view)
        var center = floatingButton.center
        center.x += offset.x
        center.y += offset.y
        floatingButton.center = center

        if panner.state == .ended || panner.state == .cancelled {
            UIView.animate(withDuration: 0.3) {
                self.snapButtonToSocket()
            }
        }
    }

    fileprivate func snapButtonToSocket() {
        guard let floatingButton = floatingButton else {return}
        var bestSocket = CGPoint.zero
        var distanceToBestSocket = CGFloat.infinity
        let center = floatingButton.center
        for socket in sockets {
            let distance = hypot(center.x - socket.x, center.y - socket.y)
            if distance < distanceToBestSocket {
                distanceToBestSocket = distance
                bestSocket = socket
            }
        }
        floatingButton.center = bestSocket
    }

    fileprivate var sockets: [CGPoint] {
        let buttonSize = floatingButton?.bounds.size ?? CGSize(width: 0, height: 0)
        let rect = view.bounds.insetBy(dx: 4 + buttonSize.width / 2, dy: 4 + buttonSize.height / 2)
        let sockets: [CGPoint] = [
            CGPoint(x: rect.minX + 15, y: rect.minY + 30),
            CGPoint(x: rect.minX + 15, y: rect.maxY - 50),
            CGPoint(x: rect.maxX - 15, y: rect.minY + 30),
            CGPoint(x: rect.maxX - 15, y: rect.maxY - 50)
        ]
        return sockets
    }
    // Custom socket position to hold Y position and snap to horizontal edges.
    // You can snap to any coordinate on screen by setting custom socket positions.
    fileprivate var horizontalSockets: [CGPoint] {
        guard let floatingButton = floatingButton else {return []}
        let buttonSize = floatingButton.bounds.size
        let rect = view.bounds.insetBy(dx: 4 + buttonSize.width / 2, dy: 4 + buttonSize.height / 2)
        let y = min(rect.maxY - 50, max(rect.minY + 30, floatingButton.frame.minY + buttonSize.height / 2))
        let sockets: [CGPoint] = [
            CGPoint(x: rect.minX + 15, y: y),
            CGPoint(x: rect.maxX - 15, y: y)
        ]
        return sockets
    }
}


override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)
        addFloatingButton()
        floatingButton?.addTarget(self, action: #selector(floatingButtonPressed), for: .touchUpInside)
    }

    @objc func floatingButtonPressed(){
        print("Floating button tapped")
    }


extension UIApplication{

    class func topViewController(controller: UIViewController? = UIApplication.shared.keyWindow?.rootViewController) -> UIViewController? {
        if let navigationController = controller as? UINavigationController {
            return topViewController(controller: navigationController.visibleViewController)
        }
        if let tabController = controller as? UITabBarController {
            if let selected = tabController.selectedViewController {
                return topViewController(controller: selected)
            }
        }
        if let presented = controller?.presentedViewController {
            return topViewController(controller: presented)
        }
        return controller
    }
}

https://stackoverflow.com/a/55159701

Cannot use mutating member on immutable value of type

func someFunc() {
    if var data = data as? ModelOne {
        data.setSub(ModelOne.SubModelOne(someVar: 2, otherVar: 1))
        self.data = data // you can do this since ModelOne conforms to SuperModel
    }
}

https://stackoverflow.com/a/38766080

Check if the current thread is the main thread

Thread.isMainThread

[NSThread isMainThread]

sort an array of objects by two keys

let sorted = array.sorted { t1, t2 in 
   if t1.isPriority == t2.isPriority {
      return t1.ordering < t2.ordering 
   }
   return t1.isPriority && !t2.isPriority 
}

https://stackoverflow.com/a/29531359

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Swift 5 Code snippets

Add leading padding to view added inside an UIStackView

Timestamp

Change year in Date

Date tomorrow

iOS local notification

Get bandle file path

Mark

Save photo to album

Copy text to the clipboard

Get configuration from PLIST

WatchOS update complications

SFSafariViewController reader mode

Change default global tint color

simulator sqlite db paths

check iCloud login

display base64 string image

SF symbols

hide files

App and build version

Providing Access to Directories

swiftlint script

Using KVO to listen to volume changes

Find list of Local Notification the app has already set

Check if remote push notifications are enabled

Change the color of a link in an NSMutableAttributedString

Present ViewController in full screen

objective-c code call swift extension

Delete all Core Data records of an entity

Notification send an object

thread-safe access

Use UIActivityIndicatorView

Swift queue

URLQueryItem

Operation and Operation Queue

Send email, sms and phone call

Set the maximum character length of a UITextField

Present view controller push animation

floating button

Cannot use mutating member on immutable value of type

Check if the current thread is the main thread

sort an array of objects by two keys

Use `UIActivityIndicatorView`

`URLQueryItem`

`Operation` and `Operation Queue`