Let’s talk about app architecture and the approach I apply as an iOS software engineer in a few companies. My team and I were trying to build something solid without slipping into a dense swamp where following the rules distracts you from actual business domain code. As a result, we got something that works for us and good enough to be told from my point of view.

UIKit first appeared in iOS 2, and it is still here. Eventually we got to know it well and learned how to work with it. We have found many architectural approaches. MVVM, the most popular architecture in my opinion, has strengthened its position with the release of SwiftUI, while other architectures seemed to have some kind of problematic relationships with SwiftUI.

But what if I told you that Clean Swift, VIPER and other approaches can be adapted to SwiftUI. What if I told you that there are some modern architectures which might be as good as MVVM or even better.

We will talk about MVI.

Only after I had published a post detailing three iOS 0-day vulnerabilities and expressing my frustration with Apple Security Bounty Program, I received a reply from Apple:

We saw your blog post regarding this issue and your other reports.

We apologize for the delay in responding to you. We want to let you know that we are still investigating these issues and how we can address them to protect customers. Thank you again for taking the time to report these issues to us, we appreciate your assistance.

Please let us know if you have any questions.

Indeed, I do have questions. The same ones that you have ignored. I'm gonna repeat them. Why was the fix for analyticsd vulnerability quietly included in iOS 14.7 update but not mentioned on its security content list? Why did you promise to include it in the next update's list but broke your words not once but trice? Why do you keep ignoring these questions?

After my previous post, some people have expressed doubts that such code can make its way into the App Store. It's understandable why they think this way. That's because Apple makes people believe that the App Store is safe by repeating it over and over. Moreover, they claim that they disallow alternative stores and application sideloading to keep users safe and otherwise they would be in great danger. Android has alternative stores and unrestricted sideloading, and have you heard about any kind of security problems with Android recently? I haven't. But it the last few months alone there were so many reports about security and privacy issues on Apple platforms. And the real reason that Apple doesn't allow any alternatives to the App Store is that they receive 30% commission on all purchases made inside any app and it's a tremendously lucrative business for them. They also enact censorship by choosing to allow or disallow any app into the App Store based purely on subjective opinions of their employees and managers.

So in this article I'm going to dispute the claim that the App Store is safe, voice my complaints about the App Store review process and provide a detailed explanation (including source code) how malicious apps on the App Store conceal their functionality from the App Store review team and are able to sneak into the App Store.

Example with JSONDecoder

struct Test<T>: Codable where T: Codable {
    enum CodingKeys: String, CodingKey {
        case value
    }
    
    let value: T
    let info: String
}

extension Test {
    init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        self.value = try container.decode(T.self, forKey: .value)
        self.info = "Default init(from decoder:)"
    }
}

extension Test where T == String {
    init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        self.value = try container.decode(T.self, forKey: .value)
        self.info = "Custom init(from decoder:)"
    }
}

let data = #"{"value":"Hello, World!"}"#.data(using: .utf8)!
let object = try? JSONDecoder().decode(Test<String>.self, from: data)
print(object.debugDescription)

Optional(
    Test<String>(
        value: "Hello, World!", 
        info: "Default init(from decoder:)"
    )
)

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.