Honghao honghaoz

If you work on a Swift project that follows the Model-View-ViewModel (MVVM) architecture or similar, you may want to jump to counterpart in Xcode from your view to your model, and then to your view model. (ie. by using Ctrl+Cmd+Up and Ctrl+Cmd+Down).

You can do this in recent versions of Xcode by setting a configuration default.

From a terminal, just type this command and press Enter:

defaults write com.apple.dt.Xcode IDEAdditionalCounterpartSuffixes -array-add "ViewModel" "View"

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

	import SwiftUI
	import Foundation
	import PlaygroundSupport

	public enum Orientation {
	case horizontal
	case vertical
	}

	public struct StackView<Content: View>: View {

	// Works on Xcode 11 GM as of 09/12/19

	// Presenting view
	// make sure the .sheet modifier is tied to the root View
	import SwiftUI

	struct ContentView: View {

	@State private var showingModalView = false

	// Don't forget to prefix your category!

	#import <UIKit/UIKit.h>

	NS_ASSUME_NONNULL_BEGIN

	@interface UIWindow (PSPDFAdditions)

	#if TARGET_OS_UIKITFORMAC

	#!/usr/bin/env python

	# Extract playlists from a non-XML iTunes Library file (.itl)
	# Copyright (c) 2018 Benno Rice, released under the BSD (2 Clause) Licence.

	# Important information on the encryption used in the .itl file found here:
	# https://mrexodia.cf/reversing/2014/12/16/iTunes-Library-Format-1
	# Highly useful information on the .itl format itself found here:
	# https://github.com/josephw/titl/blob/master/titl-core/src/main/java/org/kafsemo/titl/ParseLibrary.java

	import Foundation
	import MobileCoreServices

	struct UTType: CustomStringConvertible {
	let value: CFString
	init?(mimeType: String) {
	guard let UTI = UTTypeCreatePreferredIdentifierForTag(kUTTagClassMIMEType, mimeType as CFString, nil)?.takeUnretainedValue() else { return nil }
	value = UTI
	}

	# blog post
	#
	# https://www.jessesquires.com/blog/customizing-git-log/

	git log --graph --pretty=format:'commit: %C(bold red)%h%Creset %C(red)<%H>%Creset %C(bold magenta)%d %Creset%ndate: %C(bold yellow)%cd %Creset%C(yellow)%cr%Creset%nauthor: %C(bold blue)%an%Creset %C(blue)<%ae>%Creset%n%C(cyan)%s%n%Creset'

	let swift = UTType.swiftSource
	print(swift) // => Swift Source Code
	print(swift.rawValue) // public.swift-source
	print(swift.conforms(to: .sourceCode)) // => true
	print(swift.declaration?[.conformsTo] as Any) // [ "public.source-code" ]
	print(swift.declaringBundleURL as Any) // => /System/Library/CoreServices/MobileCoreTypes.bundle
	print(swift.isDeclared) // => true
	print(swift.isDynamic) // => false
	print(swift.preferredTag(for: .filenameExtension) as Any) // => "swift"
	print(UTType(preferredTag: "swift", for: .filenameExtension, conformingTo: nil) == swift) // => "true"

	---
	- name: Install MacOS Packages
	hosts: localhost
	become: false
	vars:
	brew_cask_packages:
	- atom
	- docker
	- dropbox
	- firefox