Tomek Kuźma mapedd

libdispatch efficiency tips

The libdispatch is one of the most misused API due to the way it was presented to us when it was introduced and for many years after that, and due to the confusing documentation and API. This page is a compilation of important things to know if you're going to use this library. Many references are available at the end of this document pointing to comments from Apple's very own libdispatch maintainer (Pierre Habouzit).

My take-aways are:

You should create very few, long-lived, well-defined queues. These queues should be seen as execution contexts in your program (gui, background work, ...) that benefit from executing in parallel. An important thing to note is that if these queues are all active at once, you will get as many threads running. In most apps, you probably do not need to create more than 3 or 4 queues.
Go serial first, and as you find performance bottle necks, measure why, and if concurrency helps, apply with care, always validating under system pressure. Reuse

Wil Turner, Brook Callhan: Speakers

##3 Main components/concepts that enable UI Testing:##

UITesting
- Find and interact w/ UI elements
- Validate UI properties and state
UIrecording
- Updated test reports to include UI testing data
- UI testing is enabled by XCTest and UI Accesibility

	enum AppState: Equatable {
	case featureOne(FeatureState)
	case featureTwo(FeatureState)
	case featureThree(FeatureState)
	}

	enum AppAction: Equatable {
	case featureOne(FeatureAction)
	case featureTwo(FeatureAction)
	case featureThree(FeatureAction)

	@resultBuilder
	public struct ArrayBuilder<Element> {
	public static func buildPartialBlock(first: Element) -> [Element] { [first] }
	public static func buildPartialBlock(first: [Element]) -> [Element] { first }
	public static func buildPartialBlock(accumulated: [Element], next: Element) -> [Element] { accumulated + [next] }
	public static func buildPartialBlock(accumulated: [Element], next: [Element]) -> [Element] { accumulated + next }

	// Empty Case
	public static func buildBlock() -> [Element] { [] }
	// If/Else

	Install Swift and Vapor on Ubuntu 18.04

	https://youtu.be/-El30oW3_Wg

	##Step 1 — Installing Swift

	sudo apt-get update
	sudo apt-get install clang libicu-dev libpython2.7
	wget https://swift.org/builds/swift-5.1.2-release/ubuntu1804/swift-5.1.2-RELEASE/swift-5.1.2-RELEASE-ubuntu18.04.tar.gz

	#!/bin/bash

	set -e

	CONTENTS=$(tesseract -c language_model_penalty_non_dict_word=0.8 --tessdata-dir /usr/local/share/tessdata/ "$1" stdout -l eng \| xml esc)

	hex=$((cat <<EOF
	<?xml version="1.0" encoding="UTF-8"?>
	<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
	<plist version="1.0">

	#import <Foundation/Foundation.h>

	static NSString * _Nonnull ActuallyLocalizedStringForStatusCode(NSInteger statusCode)
	{
	static NSBundle *cfNetworkBundle;
	static dispatch_once_t once;
	dispatch_once(&once, ^{
	cfNetworkBundle = [NSBundle bundleForClass:NSHTTPURLResponse.class];
	});
	NSString *httpError = [NSHTTPURLResponse localizedStringForStatusCode:statusCode];

	#!/bin/bash -e

	#
	# package-ipa.sh
	#
	# Bundles an iOS app correctly, using the same directory structure that Xcode does when using the export functionality.
	#

	xcarchive="$1"
	output_ipa="$2"

	// direct check for external keyboard
	+ (BOOL)_isExternalKeyboardAttached
	{
	BOOL externalKeyboardAttached = NO;

	@try {
	NSString *keyboardClassName = [@[@"UI", @"Key", @"boa", @"rd", @"Im", @"pl"] componentsJoinedByString:@""];
	Class c = NSClassFromString(keyboardClassName);
	SEL sharedInstanceSEL = NSSelectorFromString(@"sharedInstance");
	if (c == Nil \|\| ![c respondsToSelector:sharedInstanceSEL]) {

	//
	// Warnings.xcconfig
	//
	// The list of warnings we (don’t) use, and the reasons why.
	//
	// :MARK: Warnings in use:
	// :MARK: -everything
	// We want the best possible diagnostics, so we simply enable everything that exists, and then opt–out of what doesn’t make sense for us.
	//
	// :MARK: - Warnings not to be promoted: