SergLam

import UIKit

final class BubbleTriangleView: UIView {
    
    private var viewBorderWidth: CGFloat = 3
    private var radius: CGFloat = 15
    
    private var viewFillColor: UIColor = .supAzure
    private var viewBorderColor: UIColor = .white
    

SergLam

// Source - https://medium.com/@topLayoutGuide/swift-3-so-i-wanted-to-animate-a-label-14dd2b332ef9
// 
// https://github.com/dataxpress/UICountingLabel/
// 
import UIKit

enum CountingMethod {
    
    case easeInOut
    case easeIn

SergLam

import UIKit

/// Represents a single `NSLayoutConstraint`
enum LayoutAnchor {
    case constant(attribute: NSLayoutConstraint.Attribute,
                  relation: NSLayoutConstraint.Relation,
                  constant: CGFloat)

    case relative(attribute: NSLayoutConstraint.Attribute,
                  relation: NSLayoutConstraint.Relation,

SergLam

import UIKit

final class CustomVC: UIViewController {
    
    private lazy var contentView: CustomView = CustomView()
    
    // MARK: - Life cycle
    deinit {
        NotificationCenter.default.removeObserver(self)
    }

SergLam

import UIKit

protocol WordsFlexViewDelegate: class {
    func didSelectWord(word: String, intId: Int, phraseView: WordsFlexView)
}

class WordsFlexView: UIView {

    enum WordsFlexViewType {
        case selectable

SergLam

Author: https://www.cyanhall.com/

1. The Layer Tree

Core Animation's original name is Layer Kit

Core Animation is a compositing engine; its job is to compose different pieces of visual content on the screen, and to do so as fast as possible. The content in question is divided into individual layers stored in a hierarchy known as the layer tree. This tree forms the underpinning for all of UIKit, and for everything that you see on the screen in an iOS application.

In UIView, tasks such as rendering, layout and animation are all managed by a Core Animation class called CALayer. The only major feature of UIView that isn’t handled by CALayer is user interaction.

There are four hierarchies, each performing a different role:

SergLam

import UIKit

class HitTestUIView: UIView {
    override func hitTest(_ point: CGPoint, with event: UIEvent?) -> UIView? {
        if clipsToBounds || isHidden || alpha == 0 {
            return nil
        }

        for subview in subviews.reversed() {
            let subPoint = subview.convert(point, from: self)

SergLam

import Foundation

// https://en.wikipedia.org/wiki/List_of_U.S._state_and_territory_abbreviations
// https://en.wikipedia.org/wiki/ISO_3166-2

// NOTE: - Last two symbols from ISO 3166-2 state code
enum USAState: Int, CaseIterable {
    
    case alabama = 1
    case alaska = 2

SergLam

Practical code snippet that works:
https://stackoverflow.com/questions/44187881/uicollectionview-full-width-cells-allow-autolayout-dynamic-height

Theoretical material:
https://www.vadimbulavin.com/collection-view-cells-self-sizing/

SergLam

import Moya
import SwiftyJSON

enum FileWebService {
    case download(url: String, fileName: String?)
    
    var localLocation: URL {
        switch self {
        case .download(let url, let fileName):
            let fileKey: String = url.MD5 // use url's md5 as local file name