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// Taken from the commercial iOS PDF framework http://pspdfkit.com.
// Copyright (c) 2014 Peter Steinberger, PSPDFKit GmbH. All rights reserved.
// Licensed under MIT (http://opensource.org/licenses/MIT)
//
// You should only use this in debug builds. It doesn't use private API, but I wouldn't ship it.

// PLEASE DUPE rdar://27192338 (https://openradar.appspot.com/27192338) if you would like to see this in UIKit.

#import <objc/runtime.h>
#import <objc/message.h>

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import Foundation

struct AnyError: Error {

    let error: Error

    init(_ error: Error) {
        self.error = error
    }
}

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Author: https://www.cyanhall.com/

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:

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iOS CPU and GPU basics

#iOSBySheldon #CPU #GPU #60FPS #CADisplayLink

Apple always encourage us as iOS developers to try to maintain our apps running with a 60 frames per second rate (60 FPS) to make sure the best user experience. Most of the time, this comes for free because the hardwares are getting better and better.

But in some cases you may need to dig deeper if your app as a significant frame drops to fix it for the users, which leads to my post today - the basic of CPU and GPU in iOS. Whenever I encounter this kind of question, I always want to find the answer directly from Apple’s official document. I was able to find this article here. I mean this article is written mainly for #Metal and iOS game developers but I found all the info that we need. As always, I will try to summarize the best part of the article.

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The introduction to Reactive Programming you've been missing

(by @andrestaltz)

---

This tutorial as a series of videos

If you prefer to watch video tutorials with live-coding, then check out this series I recorded with the same contents as in this article: Egghead.io - Introduction to Reactive Programming.

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import UIKit

extension UIView {
    
    func createImage() -> UIImage {

        let rect: CGRect = self.frame
        
        UIGraphicsBeginImageContext(rect.size)
        let context: CGContextRef = UIGraphicsGetCurrentContext()

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import UIKit
import Photos
import Contacts
import AVFoundation

enum Permission {
    case cameraUsage
    case contactUsage
    case photoLibraryUsage