tsif

// collections

let filtered = string.filter { $0 != "🙀" }

// substrings

let substring = string[index...]

// multi line literals

tsif

/*
 *  TableViewcontroller.swift
 */


import UIKit

class TableViewcontroller: UIViewController, UITableViewDataSource, UITableViewDelegate {

    // MARK: - PROPERTIES

tsif

//: Playground - noun: a place where people can play

import UIKit
import Foundation
import PlaygroundSupport

// so we can run asynchronous code in a playground
PlaygroundPage.current.needsIndefiniteExecution = true

let iso8601Full: DateFormatter =

tsif

import Foundation
import UIKit

@objc class CollectionViewLayout: UICollectionViewLayout {
    
    var contentSize: CGSize = .zero
    var cachedAttributes = [IndexPath: UICollectionViewLayoutAttributes]()
    
    override func prepare() {
        

tsif

import CryptoKit
import Foundation

let path = Bundle.main.path(forResource: "video", ofType: "mp4")!
let data = FileManager.default.contents(atPath: path)!
let digest = SHA256.hash(data: data)
print(digest)

tsif

var hasher = SHA256()
let path = Bundle.main.path(forResource: "video", ofType: "mp4")!
let stream = InputStream(fileAtPath: path)!
stream.open()

let bufferSize = 512
let buffer = UnsafeMutablePointer<UInt8>.allocate(capacity: bufferSize)

while stream.hasBytesAvailable {
    let read = stream.read(buffer, maxLength: bufferSize)

tsif

let key = SymmetricKey(size: .bits256)

let path = Bundle.main.path(forResource: "video", ofType: "mp4")!
let data = FileManager.default.contents(atPath: path)!

// To encrypt
let encryptedData = try! ChaChaPoly.seal(data, using: key)

// To decrypt
let sealedBox = try! ChaChaPoly.SealedBox(combined: encryptedData)

tsif

let privateKey = Curve25519.Signing.PrivateKey()
let publicKey = privateKey.publicKey // publicize freely
let publicKeyData = publicKey.rawRepresentation
let signingPublicKey = try! Curve25519.Signing.PublicKey(rawRepresentation: publicKeyData)

// sign some data with your private key
let data = "All your base are belong to us".data(using: .utf8)!
let signature = try! privateKey.signature(for: data)

if signingPublicKey.isValidSignature(signature, for: data) {

tsif

let path = Bundle.main.path(forResource: "video", ofType: "mp4")!
let data = FileManager.default.contents(atPath: path)!
let key = SymmetricKey(size: .bits256) // key shared by both parties
let authentication = HMAC<SHA256>.authenticationCode(for: data,
                                                         using: key)
let authenticationData = Data(authentication)

// ~~~~~~ travel accross the network ~~~~~~~

if (HMAC<SHA256>.isValidAuthenticationCode(authenticationData,

tsif

let salt = "Salt".data(using: .utf8)!

let firstPrivateKey = P256.KeyAgreement.PrivateKey()
let firstPublicKey = firstPrivateKey.publicKey

let secondPrivateKey = P256.KeyAgreement.PrivateKey()
let secondPublicKey = secondPrivateKey.publicKey

let firstSharedSecret = try! firstPrivateKey.sharedSecretFromKeyAgreement(with: secondPublicKey)
let firstSymmetricKey = firstSharedSecret.hkdfDerivedSymmetricKey(using: SHA256.self,