m25lazi

var shouldLogTextAnalyzer = false
if ProcessInfo.processInfo.environment["text_analyzer_log"] == "verbose" {
  shouldLogTextAnalyzer = true
}

if shouldLogTextAnalyzer {
  /// Actual logger code
}

m25lazi

var shouldLogTextAnalyzer = false
if ProcessInfo.processInfo.environment["text_analyzer_log"] == "verbose" {
  shouldLogTextAnalyzer = true
}

if shouldLogTextAnalyzer {
  /// Actual logger code
}

m25lazi

import UIKit

class VerticalScrollableStackViewController: UIViewController {

    let scrollView: UIScrollView = UIScrollView(frame: .zero)
    let stackView: UIStackView = UIStackView(frame: .zero)

    override func viewDidLoad() {
        super.viewDidLoad()
        self.view.backgroundColor = .gray

m25lazi

// Pure function
func sum(_ num1: Int, _ num2: int) -> Int {
    return num1 + num2
}


// Impure function
var accumulated = 0
func add(_ num: Int) -> Int {
    accumulated = num + accumulated

m25lazi

/// Mock Subclass of ImageDownloader
/// Fetch API will return what you were passed while init.
internal class MockImageDownloader: ImageFetcher {

    typealias MockResponse = (UIImage?, Error?)

    /// Mocked response. Pass this as part of init and this will be the response of fetch API
    let mockedResponse: MockResponse

    init(url: URL, response: MockResponse) {

m25lazi

/// Interface that fetches image from a source.
/// Image can be fetched from a web service or even from a local source.
internal protocol ImageFetcher {
    func fetch(then completion: @escaping (UIImage?, Error?) -> Void)
}

/// ImageFetcher implementation to fetch image from web service
internal class ImageDownloader: ImageFetcher {
    let url: URL
    init(url: URL) {

m25lazi

/// Interface that fetches image from a source.
/// Image can be fetched from a web service or even from a local source.
internal protocol ImageFetcher {
    func fetch(then completion: @escaping (UIImage?, Error?) -> Void)
}

/// User Model
public class User {
    // Stores the
    public var name: String

m25lazi

/// Mock Subclass of ImageDownloader
/// Fetch API will return what you were passed while init.
internal class MockImageDownloader: ImageDownloader {

    typealias MockResponse = (UIImage?, Error?)

    /// Mocked response. Pass this as part of init and this will be the response of fetch API
    let mockedResponse: MockResponse

    init(url: URL, response: MockResponse) {

m25lazi

/// Injecting fetcher to the fetch API, so that we get control of downloading outside of the User class
func fetchProfileImage(fetcher: ImageDownloader, then completion: @escaping (Bool)-> Void) {
    fetcher.fetch { (image, error) in
        if let fetchError = error {
            print("Failed to fetch Image with error - \(fetchError)")
            completion(false)
        } else if let fetchedImage = image {
            print("Image fetched")
            self.iProfileImage = fetchedImage
            completion(true)

m25lazi

import Foundation
import UIKit

internal class ImageDownloader {
    let url: URL
    init(url: URL) {
        self.url = url
    }

    func fetch(then completion: @escaping (UIImage?, Error?) -> Void) {