Despite the number, this is the third article about reactive programming. Today we are going to talk about how to handle side effects while using unidirectional approaches.

Recently I wrote an article What is Reactive Programming? iOS Edition where in a simple way I described how to build your own Reactive Framework, and helped you to understand that no-one should be scared by the reactive approach. The previous article could now be named How to cook reactive programming. Part 0., since this is a continuation. I would recommend reading the previous article if you are not familiar with the reactive programming concepts.

Instruments for Apple's Xcode is a tool for performance analysis of an iOS application. In 2018 Apple introduced Custom Instruments — an opportunity to expand the standard set of instruments for application profiling. When existing tools are not enough, you can create new ones yourself — it will collect, analyze and display the data the way you need.

• Create UserView
• Create NavigationView
• Create BottomBarView
• Create SwipeView
• Put all this together inside ContentView

Human pose estimation

A few months ago I came across one interesting open source project on the Internet — Openpose the aim of which is to estimate a human pose in real-time on a video stream. Due to my professional activities, I was interested to run it on the latest iOS device from Apple to check the performance and figure out if it is possible at all. It was also interesting to see how the performance of the neural network framework for iOS has been changed in the last years.

Preface

This article is an example of how we can do research into Swift Standard Library functions behavior building our knowledge not only on the Library documentation but also on its source code.

Unrecoverable Errors

All events which programmers call "errors" can be separated into two types.

• Events caused by external factors such as a network connection failure.
• Events caused by a programmer's mistake such as reaching a switch operator case which should be unreachable.

Solution overview

Swift 5 for Xcode 10.2 beta

Swift

Apple Swift version 5.0 (swiftlang-1001.0.45.7 clang-1001.0.37.7)
Target: x86_64-apple-darwin18.2.0
ABI version: 0.6

Swift apps no longer include dynamically linked libraries for the Swift standard library and Swift SDK overlays in build variants for devices running iOS 12.2, watchOS 5.2, and tvOS 12.2. As a result, Swift apps can be smaller when deployed for testing using TestFlight, or when thinning an app archive for local development distribution.