Andriy andreyz

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

React & Elm inspired frameworks in Swift

This is a curated list of iOS (Swift & ObjC) frameworks which are inspired by React and Elm.

Swift frameworks

React-inspired

ReactSwift by @ColinEberhardt
https://github.com/ColinEberhardt/ReactSwift

	// Copyright © 2019 Simon Strandgaard. All rights reserved.
	import SwiftyBeaver

	public let log = SwiftyBeaver.self

	extension BaseDestination.LevelColor {
	mutating func applyDefaultStyle() {
	debug = "🏐 "
	info = "🏐 "
	verbose = "🏐 "

	/**
	This sample code is available under the MIT license.
	*/

	@available(iOS 12.0, *)
	public final class ShortcutManager {

	/**
	This enum specifies the different intents available in our app and their various properties for the `INIntent`.
	Replace this with your own shortcuts.

	import CoreData
	import Foundation

	/// Safely copies the specified `NSPersistentStore` to a temporary file.
	/// Useful for backups.
	///
	/// - Parameter index: The index of the persistent store in the coordinator's
	/// `persistentStores` array. Passing an index that doesn't exist will trap.
	///
	/// - Returns: The URL of the backup file, wrapped in a TemporaryFile instance

	import XCTest

	/// An expectation that is fulfilled when a Key Value Observing (KVO) condition
	/// is met. It's variant of `XCTKVOExpectation` with support for native Swift
	/// key paths.
	final class KVOExpectation: XCTestExpectation {
	private var kvoToken: NSKeyValueObservation?

	/// Creates an expectation that is fulfilled when a KVO change causes the
	/// specified key path of the observed object to have an expected value.

	extension UITabBarController {

	/**
	Show or hide the tab bar.

	- Parameter hidden: `true` if the bar should be hidden.
	- Parameter animated: `true` if the action should be animated.
	- Parameter transitionCoordinator: An optional `UIViewControllerTransitionCoordinator` to perform the animation
	along side with. For example during a push on a `UINavigationController`.
	*/

	//: [Previous](@previous)

	import Foundation

	struct AnyEquatable {
	private let isEqualTo: (Any) -> Bool
	let value: Any

	init<A: Equatable>(_ value: A) {
	self.value = value

	//
	// main.swift
	// ExtensibleEffects
	//
	// Created by Chris Eidhof on 02.01.18.
	// Copyright © 2018 objc.io. All rights reserved.
	//

	import Foundation

	//
	// UIView+SafeAnchors.swift
	//

	extension UIView {

	var safeTopAnchor: NSLayoutYAxisAnchor { return optionalSafeAreaLayoutGuide?.topAnchor ?? topAnchor }
	var safeBottomAnchor: NSLayoutYAxisAnchor { return optionalSafeAreaLayoutGuide?.bottomAnchor ?? bottomAnchor }

	var safeLeftAnchor: NSLayoutXAxisAnchor { return optionalSafeAreaLayoutGuide?.leftAnchor ?? leftAnchor }