Yiming Tang yimingtang

1. The Layer Tree

Core Animation's original name is Layer Kit

Core Animation is a compositing engine; its job is to compose different pieces of visual content on the screen, and to do so as fast as possible. The content in question is divided into individual layers stored in a hierarchy known as the layer tree. This tree forms the underpinning for all of UIKit, and for everything that you see on the screen in an iOS application.

In UIView, tasks such as rendering, layout and animation are all managed by a Core Animation class called CALayer. The only major feature of UIView that isn’t handled by CALayer is user interaction.

There are four hierarchies, each performing a different role:

Below is just about everything you'll need to style in the theme. Check the source code to see the many embedded elements within paragraphs.

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Apps to install from macOS App Store:

Pastebot
GIF Brewery
Slack
Keynote/Pages/Numbers
1Password
OmniFocus 3
Airmail 3
iA Writer

FFmpeg Cheat Sheet for 360º video

Brought to you by Headjack

FFmpeg is one of the most powerful tools for video transcoding and manipulation, but it's fairly complex and confusing to use. That's why I decided to create this cheat sheet which shows some of the most often used commands.

Let's start with some basics:

ffmpeg calls the FFmpeg application in the command line window, could also be the full path to the FFmpeg binary or .exe file

	extension UIImage {
	public func imageRotatedByDegrees(degrees: CGFloat) -> UIImage {
	let radiansToDegrees: (CGFloat) -> CGFloat = {
	return $0 * (180.0 / CGFloat(M_PI))
	}
	let degreesToRadians: (CGFloat) -> CGFloat = {
	return $0 / (180.0 * CGFloat(M_PI))
	}

	// calculate the size of the rotated view's containing box for our drawing space

	/// Observes a run loop to detect any stalling or blocking that occurs.
	///
	/// This class is thread-safe.
	@interface GHRunLoopWatchdog : NSObject

	/// Initializes the receiver to watch the specified run loop, using a default
	/// stalling threshold.
	- (id)initWithRunLoop:(CFRunLoopRef)runLoop;

	/// Initializes the receiver to detect when the specified run loop blocks for

	// #!Swift-1.1
	import Foundation


	// MARK: - (1) classes

	// Solution 1:
	// - Use classes instead of struct
	// Issue: Violate the concept of moving model to the value layer
	// http://realm.io/news/andy-matuschak-controlling-complexity/

	/----------------------------------------------------/
	#pragma mark - XCTAsserts
	/----------------------------------------------------/

	XCTAssert(expression, format...);
	XCTAssertTrue(expression, format...);
	XCTAssertFalse(expression, format...);
	XCTAssertEqual(expression1, expression2, format...);
	XCTAssertNotEqual(expression1, expression2, format...);
	XCTAssertNil(expression, format...);

	from math import sqrt, pow, sin, cos
	from math import pi as M_PI
	M_PI_2 = M_PI * 2

	'''
	original c code:
	https://raw.githubusercontent.com/warrenm/AHEasing/master/AHEasing/easing.c
	Copyright (c) 2011, Auerhaus Development, LLC
	http://sam.zoy.org/wtfpl/COPYING for more details.
	'''


	/*
	ArrayUtil exposes a set of helper methods for working with
	ReadableArray (by React Native), Object[], and JSONArray.

	MIT License

	Copyright (c) 2020 Marc Mendiola

	Permission is hereby granted, free of charge, to any person obtaining a copy