imjhk03

extension StringProtocol {
	
	subscript(_ offset: Int) -> String.Element {
		if offset >= 0 {
			self[index(startIndex, offsetBy: offset)]
		} else {
			self[index(endIndex, offsetBy: offset)]			
		}
	}
	

imjhk03

import Algorithms

// The ~= operator means "contains", and is used to test if a value is within a range.
let seq = 9...13
print(seq ~= 9)   // true
print(seq ~= 50)  // false

// The .adjacentPairs() method lets you iterate through a sequence in pairs of current + next.
let pairs = ["a", "b", "c", "d"].adjacentPairs()
for pair in pairs { print(pair) }   // ("a", "b"), ("b", "c"), ("c", "d")

imjhk03

import Foundation

/// Find specific character in String using String.Index (Unicode-compliant way)
/// Usage:
/// let word = "Banana"
/// let fifthCharacter = word[4]
/// print("The 5th character is: \(fifthCharacter)") // Prints: The 5th character is: n
extension StringProtocol {
    subscript(offset: Int) -> Character {
        self[index(startIndex, offsetBy: offset)]

imjhk03

// Changing the most recent commit message
1. Run 'git commit --amend' in terminal
2. Edit the commit message
3. Save and close the opened default text editor

imjhk03

// Initialize an array with fixed number of default values
var digitCounts = Array(repeating: 0, count: 5)
// [0, 0, 0, 0, 0]

// Convert an array of integers to an array of strings, use 'map()'
let numbers: [Int] = [1, 2, 3, 4, 5]
let stringArray = numbers.map { String($0) }

// Find the maximum element in an array, can be nil
let numbers = [1, 2, 3, 4, 5]

imjhk03

extension View {
    func hostingView() -> UIView {
        let hostingView = UIHostingController(rootView: self)
        return hostingView.view
    }
}

imjhk03

enum OpenURL {
    enum Scheme {
        case url(String)
        case tel(String)
        case app(String)
    }
    
    static func open(scheme: OpenURL.Scheme, completion: ((Bool) -> Void)? = nil) {
        let application = UIApplication.shared
        let url: URL

imjhk03

class SwipeBackGestureViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        navigationController?.hidesBarsOnSwipe = true
        navigationController?.interactivePopGestureRecognizer?.delegate = self
    }

    override func viewDidAppear(_ animated: Bool) {

imjhk03

1. Using Markup
Single Line comment
//: line of markup content

Multi Line Comment
/*:
  ...
*/

2. Headings

imjhk03

import Foundation

enum Dough: String {
    case basic
    case cheeseCrust
}

enum Topping: String, CaseIterable {
    case pepperoni
    case sausage