Christopher Karani christopherkarani

iOS Interview Questions

Sources include, but not limited to:

In Swift, what is the difference between a struct and a class?

Swift Concurrency Manifesto

Author: Chris Lattner

Chinese Translation by Jason Yu

Async/Await for Swift

Proposal: SE-XXXX
Authors: Chris Lattner, Joe Groff

Introduction

Modern Cocoa development involves a lot of asynchronous programming using closures and completion handlers, but these APIs are hard to use. This gets particularly problematic when many asynchronous operations are used, error handling is required, or control flow between asynchronous calls gets complicated. This proposal describes a language extension to make this a lot more natural and less error prone.

This paper introduces a first class Coroutine model to Swift. Functions can opt into to being async, allowing the programmer to compose complex logic involving asynchronous operations, leaving the compiler in charge of producing the necessary closures and state machines to implement that logic.

Using Swift Package Manager with iOS

Step 1:

File > New > Project...

Step 2:

Create a Package.swift file in your root project directory, add dependencies, then run swift package fetch on the command line in the same directory. We’re not going to run swift build because it will just complain.

	#!/bin/bash
	# Set up a Raspberry Pi 4 as a USB-C Ethernet Gadget
	# Based on:
	# - https://www.hardill.me.uk/wordpress/2019/11/02/pi4-usb-c-gadget/
	# - https://pastebin.com/VtAusEmf

	if ! $(grep -q dtoverlay=dwc2 /boot/config.txt) ; then
	echo "Add the line dtoverlay=dwc2 to /boot/config.txt"
	exit
	fi

	/// A class of types whose instances hold the value of an entity with stable identity.
	protocol Identifiable {

	/// A type representing the stable identity of the entity associated with `self`.
	associatedtype ID: Hashable

	/// The stable identity of the entity associated with `self`.
	var id: ID { get }
	}

	Development Phase:

	Step 1: Create Certificate .pem from Certificate .p12
	Command: openssl pkcs12 -clcerts -nokeys -out apns-dev-cert.pem -in apns-dev-cert.p12

	Step 2: Create Key .pem from Key .p12
	Command : openssl pkcs12 -nocerts -out apns-dev-key.pem -in apns-dev-key.p12

	Step 3: Optional (If you want to remove pass phrase asked in second step)
	Command : openssl rsa -in apns-dev-key.pem -out apns-dev-key-noenc.pem

	let countries = [
	"AF - Afghanistan",
	"AX - Aland Islands",
	"AL - Albania",
	"DZ - Algeria",
	"AS - American Samoa",
	"AD - Andorra",
	"AO - Angola",
	"AI - Anguilla",
	"AQ - Antarctica",

	import UIKit

	extension String {
	var hexColor: UIColor? {
	let hex = self.stringByTrimmingCharactersInSet(NSCharacterSet.alphanumericCharacterSet().invertedSet)
	var int = UInt32()
	guard NSScanner(string: hex).scanHexInt(&int) else {
	return nil
	}
	let a, r, g, b: UInt32

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

	import UIKit

	let fontURL = NSBundle.mainBundle().URLForResource("PillGothic300mg-bold", withExtension: "ttf")
	CTFontManagerRegisterFontsForURL(fontURL!, CTFontManagerScope.Process, nil)

	var pillGothicFontBold = UIFont(name: "PillGothic300mg-bold", size: 30)

	var attrs = [NSFontAttributeName : pillGothicFontBold!,