Ben Surtees bensurtees

The dynamic wallpaper in MacOS Mojave is a single 114 MB .heic file that seems to contain 16 embedded images.

It also contains the following binary plist data in its metadata under the key "Solar". It's an array of 16 items, each with four keys:

i (integer). This seems to be the image index.
o (integer). This is always 1 or 0. Stephen Radford thinks it indicates dark mode (0) vs. light mode (1).
a (decimal). I’m pretty sure this is the angle of the sun over the horizon. 0º = sunset/sunrise. 90º = sun directly overhead. Negative values = sun below horizon.
z (decimal). This seems to be the cardinal position of the sun relative to the camera. 0º = sun is directly in front of the camera. 90º = sun is directly to the right of the camera. 180º = sun is directly behind the camera.

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

	on setDarkMode(shouldBeDark)

	set paneID to "com.apple.preference.general"

	tell application "System Events"
	if dark mode of appearance preferences is shouldBeDark then return
	end tell

	set paneWasOpen to false

	<?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">
	<!-- iOS 10, macOS Sierra, and friends bring a new logging subsystem that's
	supposed to scale from the kernel, up to frameworks, and up to apps. It defaults
	to a more regimented, privacy-focused approach that large apps and complex
	systems need.

	It, along with Activity Tracing introduced in iOS 8 and macOS Yosemite and the
	Console app in macOS Sierra, hope to help you graduate from caveman debugging to

	/// header

	id CGSCopyManagedDisplaySpaces(int conn);
	int _CGSDefaultConnection();
	id CGSCopyWindowsWithOptionsAndTags(int conn, unsigned owner, NSArray spids, unsigned options, unsigned long long setTags, unsigned long long *clearTags);


	// code

	int spaceNumber = 0; // the space you want to get the windows for. numbering starts at 0.

	/* re-implementation of the behaviour that the /usr/bin/defaults application
	* uses to read sandboxed preference data */

	#include <CoreFoundation/CoreFoundation.h>

	#define EX_BUNDLE_ID "com.apple.mail"
	#define EX_KEY "JunkMailBehavior"

	// undocumented, internal CFPreferences API call
	extern CFDictionaryRef _CFPreferencesCopyApplicationMap(CFStringRef userName, CFStringRef hostName);

	##
	# OSX defaults, based on http://mths.be/osx
	#

	# Ask for the administrator password upfront
	sudo -v

	# Set computer name (as done via System Preferences → Sharing)
	sudo scutil --set ComputerName "air"
	sudo scutil --set HostName "air"

	#include <assert.h>
	#include <stdbool.h>
	#include <sys/types.h>
	#include <unistd.h>
	#include <sys/sysctl.h>

	static bool AmIBeingDebugged(void)
	// Returns true if the current process is being debugged (either
	// running under the debugger or has a debugger attached post facto).
	{

	#!/bin/sh

	###
	# SOME COMMANDS WILL NOT WORK ON macOS (Sierra or newer)
	# For Sierra or newer, see https://github.com/mathiasbynens/dotfiles/blob/master/.macos
	###

	# Alot of these configs have been taken from the various places
	# on the web, most from here
	# https://github.com/mathiasbynens/dotfiles/blob/5b3c8418ed42d93af2e647dc9d122f25cc034871/.osx