singleton vs Singleton

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let cancelAction = UIAlertAction(title: &lt;#T##String?#&gt;, style: .cancel, handler: nil)

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@IBAction func doSomething()
@IBAction func doSomething(sender: UIButton)
@IBAction func doSomething(sender: UIButton, forEvent event: UIEvent)

[[NSProcessInfo processInfo] operatingSystemVersion]

override func viewDidLoad() {
    super.viewDidLoad()
    // Swift block syntax (iOS 10+)
    let timer = Timer(timeInterval: 0.4, repeats: true) { _ in print("Done!") }
    // Swift >=3 selector syntax
    let timer = Timer.scheduledTimer(timeInterval: 0.4, target: self, selector: #selector(self.update), userInfo: nil, repeats: true)
    // Swift 2.2 selector syntax
    let timer = NSTimer.scheduledTimerWithTimeInterval(0.4, target: self, selector: #selector(MyClass.update), userInfo: nil, repeats: true)
    // Swift <2.2 selector syntax
    let timer = NSTimer.scheduledTimerWithTimeInterval(0.4, target: self, selector: "update", userInfo: nil, repeats: true)
}

// must be internal or public. 
@objc func update() {
    // Something cool
}

import StoreKit

//inside viewController
let productId = "your_product_id"


//Action where you want to trigger the purchase
@IBAction func btn_OneTimeButtonClicked(_ sender: UIButton) {
	if SKPaymentQueue.canMakePayments(){
		let paymentRequest = SKMutablePayment()
		paymentRequest.productIdentifier = productId
		SKPaymentQueue.default().add(paymentRequest)
	}
}

//extension to handle the transaction states

extension your_View_Controller: SKPaymentTransactionObserver{
    func paymentQueue(_ queue: SKPaymentQueue, updatedTransactions transactions: [SKPaymentTransaction]) {
        transactions.forEach { transaction in
            switch transaction.transactionState{
            case .purchasing:
                print("purchasing now ...")
            case .purchased:
                print("purchase successful !!!")
            case .failed:
                print("purchase failed !!!")
            case .restored:
                print("purchase restored !!!")
            case .deferred:
                print("purchase deferred !!!")
            @unknown default:
                print("Unknown error")
            }
        }
    }
}

// don't forgot to add storekit configuration file in your app if you are testing your app in simulator

//Here is signleton - that means you can create an object of a class outside it

class singleton{
  
  static let shared = singleton()
  init(){} //(Optional to do it or not)
  
  let temp = 5

}

//Usage

viewDidLoad(){
  let num = singleton.shared.temp
  
  //but also you can create object
  let obj = singleton()
  let num = obj.temp
}


//Here is Signleton - that means you cannot create an object of a class outside it

class Singleton{
  
  static let shared = singleton()
  private init(){} //(Optional to do it or not)
  
  let temp = 5

}

//Usage

viewDidLoad(){
  let num = singleton.shared.temp
  
  //but you cannot create object
  //let obj = singleton()
  //let num = obj.temp
}

Purchases.shared.delegate = self

extension YourClass: PurchasesDelegate {
    func purchases(_ purchases: Purchases, receivedUpdated customerInfo: Purchases.CustomerInfo) {
        if let entitlement = customerInfo.entitlements["your_entitlement_id"] {
            if entitlement.isActive == false {
                // subscription has expired
                print("Subscription has expired")
            } else {
                // subscription is active
                print("Subscription is active")
            }
        }
    }
}

// Preferred status bar style lightContent to use on dark background.
// Swift 3
override var preferredStatusBarStyle: UIStatusBarStyle {
    return .lightContent
}

// MARK: - Properties

// MARK: - IBOutlets

// MARK: - Life cycle

// MARK: - Set up

// MARK: - IBActions

// MARK: - Navigation

// MARK: - Network Manager calls

// MARK: - Extensions

import UIKit

extension UITableView {
    
    func dequeueReusableCell<T: UITableViewCell>() -> T {
        return dequeueReusableCell(withIdentifier: NSStringFromClass(T.self)) as! T
    }
}

//using: let cell: ExampleTableViewCell = tableView.dequeueReusableCell()

#include <iostream>
#include "unordered_set"
#include "basicActions.h"
using namespace std;

void createLoop(Node *head)
{
    Node *p = head;

    while (p->next != nullptr)
    {
        p = p->next;
    }
    p->next = head;
    return;
}

bool detectLoop(Node *head)
{
    unordered_set<Node *> s;
    Node *p = head;

    while (p != nullptr)
    {
        if (s.find(p) != s.end())
            return true;

        s.insert(p);
        p = p->next;
    }
    return false;
}

int main()
{
    Node *head = nullptr;
    insertAtEnd(head, 1);
    insertAtEnd(head, 2);
    insertAtEnd(head, 3);
    insertAtEnd(head, 4);
    insertAtEnd(head, 5);

    createLoop(head);

    detectLoop(head) ? cout << "Loop Detected.." << '\n' : cout << "No Loop Detected.." << '\n';
}

#include <iostream>
using namespace std;

struct hashing
{
    int value;
    int key;
};


void put(int value, hashing hash[],int n) {
    hash[value % n].value = value;
    hash[value % n].key = (value % n);
}

int get(int key, hashing hash[]) {
    return hash[key].value;
}

int main()
{
    int n;
    
    struct hashing hash[n];
    cin >> n;
    for (int t=0;t<n;t++) {
        put(t+1,hash,n);
        cout << "Inserted : " << (t+1) << endl;
    }
    int temp;
    cin >> temp;
    cout << get(temp,hash) << endl;
}

let url = URL(string: image.url)
let data = try? Data(contentsOf: url!) //make sure your image in this url does exist, otherwise unwrap in a if let check / try-catch
imageView.image = UIImage(data: data!)

//
//  GoogleSignInButtonView.swift
//
//  Created by Ivan Schaab on 11/09/2019.
//  Copyright © 2019 Ivan Schaab. All rights reserved.
//
import GoogleSignIn
import SwiftUI

struct GoogleSignInButtonView: View {

    @EnvironmentObject var lvm: LoginViewModel

    var body: some View {
        HStack {
            Spacer()
            GoogleButtonViewControllerRepresentable { (token, user) in
                // Google Login Success
                // Now do Backend Validations
                self.lvm.loginOauth(token: token, user: user)
            }
            Spacer()
        }.frame(alignment: .center)
    }
}

class GoogleButtonUIKitViewController: UIViewController {

    var signInButton = GIDSignInButton()

    override func viewDidLoad() {
        super.viewDidLoad()

        GIDSignIn.sharedInstance().clientID = Constants.GOOGLE_CLIENT_ID
        self.view.addSubview(signInButton)

        GIDSignIn.sharedInstance()?.presentingViewController = self

        // Automatically sign in the user.
        GIDSignIn.sharedInstance()?.restorePreviousSignIn()
    }
}

struct GoogleButtonViewControllerRepresentable: UIViewControllerRepresentable
{
    let vc = GoogleButtonUIKitViewController()
    var googleResponse: (String, User) -> Void

    func makeUIViewController(context: Context) -> GoogleButtonUIKitViewController {
        return vc
    }
    func updateUIViewController(_ uiViewController: GoogleButtonUIKitViewController, context: Context) {}
    func makeCoordinator() -> Coordinator {
        Coordinator(vc: vc, googleResponse: googleResponse)
    }

    static func dismantleUIViewController(_ uiViewController: GoogleButtonUIKitViewController, coordinator: GoogleButtonViewControllerRepresentable.Coordinator) {
        print("DISMANTLE")
    }

    class Coordinator: NSObject, GIDSignInDelegate  {
        var foo: (String, User) -> Void
        init(vc: GoogleButtonUIKitViewController, googleResponse: @escaping (String, User) -> Void) {
            self.foo = googleResponse
            super.init()
            GIDSignIn.sharedInstance()?.delegate = self
        }

        func sign(_ signIn: GIDSignIn!, didSignInFor googleUser: GIDGoogleUser!, withError error: Error!) {
            if let error = error {
                if (error as NSError).code == GIDSignInErrorCode.hasNoAuthInKeychain.rawValue {
                    print("The user has not signed in before or they have since signed out.")
                } else {
                    print("\(error.localizedDescription)")
                }
                return
            }
//            let userId = googleUser.userID                  // For client-side use only!
            let idToken = googleUser.authentication.idToken // Safe to send to the server
            let email = googleUser.profile.email

            if googleUser.profile.hasImage{
                let imageUrl = googleUser.profile.imageURL(withDimension: 120)
                print(" image url: ", imageUrl?.absoluteString ?? "NO URL")
            }

            let user : User = User(id: 1, name: googleUser.profile.givenName, surname: googleUser.profile.familyName, imgName: ""  , email: googleUser.profile.email)

            print("email: ",email ?? "NO EMAIL")

            foo(idToken! , user)
        }
    }
}



#if DEBUG
struct SomeRepView_Previews: PreviewProvider {
    static var previews: some View {
        GoogleSignInButtonView().environmentObject(LoginViewModel())
    }
}
#endif

private func deviceTokenDataToString(_ deviceToken: Data) -> String {
        let tokenChars = (deviceToken as NSData).bytes.assumingMemoryBound(to: CChar.self)
        var tokenString = ""

        for i in 0..<deviceToken.count {
            tokenString += String(format: "%02.2hhx", arguments: [tokenChars[i]])
        }

        return tokenString
    }

   func updateDeviceToken() {
        guard let deviceToken: Data = dataStorageService.value(for: .pushDeviceToken),
            deviceToken.isEmpty == false else {
                return
        }
        let stringPushToken = deviceTokenDataToString(deviceToken)
        mixpanel?.track(event: "Push Token Updated", properties: ["token": stringPushToken])
        peopleObject?.people.set(properties: ["$ios_devices": [stringPushToken]]
        mixpanel?.flush()
    }