https://mfaani.com/ Recent content on TIL with Mohammad Hugo -- gohugo.io en-us Wed, 03 Dec 2025 02:26:45 -0500 https://mfaani.com/posts/architecture/1-statedriven-navigation-overview/ Wed, 03 Dec 2025 02:26:45 -0500 https://mfaani.com/posts/architecture/1-statedriven-navigation-overview/ Why direct view-to-view navigation breaks down at scale, and how a state machine with a dedicated navigation layer creates maintainable, testable mobile apps. https://mfaani.com/posts/architecture/2-statedriven-navigation-tutorial/ Tue, 02 Dec 2025 02:26:45 -0500 https://mfaani.com/posts/architecture/2-statedriven-navigation-tutorial/ Dead simple, concrete examples of state-driven navigation. Build a 3-screen onboarding flow from scratch. https://mfaani.com/posts/swift/concurrency/what-does-actor-reentrancy-mean/ Tue, 11 Nov 2025 06:35:05 -0400 https://mfaani.com/posts/swift/concurrency/what-does-actor-reentrancy-mean/ If you captured any state before doing some async work in your actor, then by the time your task is resumed, your captured state may be stale. This is what actor reentrancy is about. Because of this, you should avoid capturing things that are subject to change before your task is suspended. Instead, only retrieve values after your task is resumed. The term “reentrant” literally means “able to be entered again. https://mfaani.com/posts/interviewing/system-design/pagination/ Thu, 06 Nov 2025 03:55:58 -0400 https://mfaani.com/posts/interviewing/system-design/pagination/ How does Base 64, cursor collision, security, deletion of a cursor all come together, caching and stale data management https://mfaani.com/posts/ios/swiftui-camera-learnings/ Sat, 02 Aug 2025 11:57:25 -0400 https://mfaani.com/posts/ios/swiftui-camera-learnings/ I used the following tutorial series from Apple on ‘Capturing and Displaying Photos’. They’re great. Just that it took me a bit to be able to piece together how components from AVFoundation work together. Working with AVFoundation isn’t really the kind where you read documentation and then can piece things together. It’s complicated. You might understand an individual step, but won’t understand when it should be done. There’s just too many components and while it’s not low-level, it’s certainly a different kind of iOS. https://mfaani.com/posts/swift/concurrency/what-is-a-suspension-point/ Thu, 10 Jul 2025 13:48:29 -0400 https://mfaani.com/posts/swift/concurrency/what-is-a-suspension-point/ Ever wondered what is getting suspended when Apple says 'suspension point'? https://mfaani.com/posts/liveactivities/1-intro/ Wed, 16 Apr 2025 08:00:04 -0400 https://mfaani.com/posts/liveactivities/1-intro/ A laundry list on Live Activity challenges https://mfaani.com/posts/liveactivities/2-the-missing-doc/ Wed, 16 Apr 2025 08:00:03 -0400 https://mfaani.com/posts/liveactivities/2-the-missing-doc/ Let's answer some lesser discussed architectural questions about Live Activities https://mfaani.com/posts/liveactivities/3-development/ Wed, 16 Apr 2025 08:00:02 -0400 https://mfaani.com/posts/liveactivities/3-development/ Some tips for developing live activities and understanding its architecture https://mfaani.com/posts/liveactivities/4-debugging/ Wed, 16 Apr 2025 08:00:01 -0400 https://mfaani.com/posts/liveactivities/4-debugging/ Sharing some tips on how to troubleshoot cases where tokens aren't getting updated or payload isn't getting updated. Or often payload is delivered but dropped by the app. https://mfaani.com/posts/liveactivities/5-product-decisions/ Wed, 16 Apr 2025 08:00:00 -0400 https://mfaani.com/posts/liveactivities/5-product-decisions/ Key product decisions that may help to achieve a better Live Activity User Experience https://mfaani.com/posts/swift/concurrency/swift-actors-a-few-random-notes/ Fri, 11 Apr 2025 10:35:05 -0400 https://mfaani.com/posts/swift/concurrency/swift-actors-a-few-random-notes/ Curious about why Swift's thread-safety mechanism is called an 'actor'? This post explores the origin of the name, clarifies common misconceptions, and explains why actors are about more than just asynchronous programming. Discover when to use actors in your Swift code and how they fit into the broader concurrency landscape https://mfaani.com/posts/interviewing/final-round-learning/ Thu, 06 Mar 2025 03:55:58 -0400 https://mfaani.com/posts/interviewing/final-round-learning/ Discuss all aspects of interview https://mfaani.com/posts/interviewing/trees/symmetric-tree/ Sun, 12 Jan 2025 14:13:27 -0500 https://mfaani.com/posts/interviewing/trees/symmetric-tree/ A good tree traversal excercise https://mfaani.com/posts/career/why-you-should-not-use-companys-macbook-for-personal-usage/ Wed, 18 Dec 2024 18:10:19 -0500 https://mfaani.com/posts/career/why-you-should-not-use-companys-macbook-for-personal-usage/ Why having your own personal laptop is a game changer https://mfaani.com/posts/career/how-to-get-into-software-engineering/ Thu, 12 Dec 2024 22:07:25 -0500 https://mfaani.com/posts/career/how-to-get-into-software-engineering/ most people think you need to study four years to get a job in tech. That's not true https://mfaani.com/posts/swift/why-cant-you-loop-over-ranges-of-characters-in-swift/ Sat, 30 Nov 2024 13:38:24 -0500 https://mfaani.com/posts/swift/why-cant-you-loop-over-ranges-of-characters-in-swift/ Why are Swift Character ranges different from Integer ranges https://mfaani.com/posts/career/how-quantifying-impact-helps-your-career-growth/ Fri, 15 Nov 2024 12:22:07 -0500 https://mfaani.com/posts/career/how-quantifying-impact-helps-your-career-growth/ Often as engineers we do ourselves a disservice and just do the hard work without measuring its impact. This post gives you strategies to promote yourself https://mfaani.com/posts/devtools/binaries/how-do-binaries-work-together/ Sun, 20 Oct 2024 15:22:35 -0400 https://mfaani.com/posts/devtools/binaries/how-do-binaries-work-together/ Ever wondered what how two binaries interface with one another? Which changes impact ABI and which don't? https://mfaani.com/posts/swift/some-vs-any/ Wed, 17 Jul 2024 14:26:39 -0400 https://mfaani.com/posts/swift/some-vs-any/ What's the difference between some and any? Why do they both exist? Which should I prefer using? https://mfaani.com/posts/content-creation/everything-i-learned-from-blogging-with-hugo/hugo-post-formatting/ Fri, 03 May 2024 04:17:58 -0400 https://mfaani.com/posts/content-creation/everything-i-learned-from-blogging-with-hugo/hugo-post-formatting/ How to use frontmatter, shortcodes, make changes to your theme, do syntax highlighting https://mfaani.com/posts/content-creation/everything-i-learned-from-blogging-with-hugo/hugo-high-level/ Tue, 30 Apr 2024 04:17:58 -0400 https://mfaani.com/posts/content-creation/everything-i-learned-from-blogging-with-hugo/hugo-high-level/ How does Hugo work? How are things structured? What are the main building blocks of Hugo? https://mfaani.com/posts/career/being-first-is-a-game-changer/ Wed, 28 Feb 2024 08:56:08 -0500 https://mfaani.com/posts/career/being-first-is-a-game-changer/ Being a good lead is a lot about being first https://mfaani.com/posts/interviewing/dynamic-programming/the-effect-of-direction-on-recursion-and-understanding-code/ Sat, 02 Dec 2023 17:34:13 -0500 https://mfaani.com/posts/interviewing/dynamic-programming/the-effect-of-direction-on-recursion-and-understanding-code/ Solve a fun challenged named 'Longest Common Subsequence' by learning how the direction in recursion can effect your perception but also make comparing code difficult https://mfaani.com/posts/interviewing/arrays/asteroids-collision/ Mon, 20 Nov 2023 09:00:08 -0500 https://mfaani.com/posts/interviewing/arrays/asteroids-collision/ Of the most fun leetcode challenges I've ever done https://mfaani.com/posts/interviewing/dynamic-programming/how-many-envelopes-can-you-fit-into-another/ Sun, 12 Nov 2023 10:40:49 -0400 https://mfaani.com/posts/interviewing/dynamic-programming/how-many-envelopes-can-you-fit-into-another/ Learn how to solve a challenging problem from LeetCode using dynamic programming and binary search. Find the longest increasing sequence of envelopes that can be nested inside each other. https://mfaani.com/posts/interviewing/dynamic-programming/longest-increasing-subsequence-length/ Sat, 11 Nov 2023 19:30:38 -0500 https://mfaani.com/posts/interviewing/dynamic-programming/longest-increasing-subsequence-length/ Learn how to calculate the longest increasing subsequence. The differences of this with other tree based algorithms and more https://mfaani.com/posts/content-creation/everything-i-learned-from-blogging-with-hugo/how-to-start-writing-a-post/ Sun, 01 Oct 2023 04:17:58 -0400 https://mfaani.com/posts/content-creation/everything-i-learned-from-blogging-with-hugo/how-to-start-writing-a-post/ Discussion about when you should start blogging, the importance of getting early feedback and how to get it, how to market your posts and more https://mfaani.com/posts/interviewing/trees/tree-basics/ Mon, 11 Sep 2023 11:16:01 -0400 https://mfaani.com/posts/interviewing/trees/tree-basics/ Some gotchas with different kinds of trees, tree mappings and traversals https://mfaani.com/posts/devtools/optimizing-app-size/how-can-i-inspect-the-size-impact-of-symbols-in-an-app-binary/ Fri, 11 Aug 2023 16:21:06 -0400 https://mfaani.com/posts/devtools/optimizing-app-size/how-can-i-inspect-the-size-impact-of-symbols-in-an-app-binary/ Learn how to use nm to count extra symbols that impact App Size https://mfaani.com/posts/devtools/optimizing-app-size/how-does-the-linker-help-reduce-app-size-part-two/ Tue, 04 Jul 2023 15:04:28 -0500 https://mfaani.com/posts/devtools/optimizing-app-size/how-does-the-linker-help-reduce-app-size-part-two/ In this post I go through some of differences between the two linkers, their impact on app size and how we should be considerate of stripping symbols https://mfaani.com/posts/devtools/optimizing-app-size/how-does-the-linker-help-reduce-app-size-part-one/ Tue, 04 Jul 2023 15:04:27 -0500 https://mfaani.com/posts/devtools/optimizing-app-size/how-does-the-linker-help-reduce-app-size-part-one/ In this post I extract all the good chunks from Apple's fantastic session on linker and how it does things to reduce app size. I also discuss some of the difference between Compiler and Linker https://mfaani.com/posts/devtools/optimizing-app-size/jargon/ Wed, 31 May 2023 09:03:27 -0500 https://mfaani.com/posts/devtools/optimizing-app-size/jargon/ Jargons and Examples of the Xcode Build Pipeline https://mfaani.com/posts/devtools/optimizing-app-size/build-pipeline/ Wed, 03 May 2023 15:01:27 -0500 https://mfaani.com/posts/devtools/optimizing-app-size/build-pipeline/ Ever thought what happens under the hood when you build your app? https://mfaani.com/posts/devtools/whats-the-difference-between-an-app-bundle-and-a-binary/ Tue, 28 Mar 2023 00:00:37 -0400 https://mfaani.com/posts/devtools/whats-the-difference-between-an-app-bundle-and-a-binary/ How the their internals are different and where they're used https://mfaani.com/posts/swift/the-power-and-expressiveness-of-swift-ranges/ Fri, 10 Mar 2023 09:51:10 -0500 https://mfaani.com/posts/swift/the-power-and-expressiveness-of-swift-ranges/ Ranges in swift are super simple to create. Yet they come in various forms. let r1 = 1...3 let r2 = 1..<3 let r3 = ...3 let r4 = 3... let r5 = ..<3 They all have range like characteristics, but have slightly different traits. It’s because they’re actually different types. Different Range Types let r1 = 1...3 // ClosedRange<Int> let r2 = 1..<3 // Range<Int> let r3 = ...3 // PartialRangeThrough<Int> let r4 = 3. https://mfaani.com/posts/devtools/how-cp-case-insensitivity-can-cause-chaos/ Tue, 06 Dec 2022 21:20:30 -0500 https://mfaani.com/posts/devtools/how-cp-case-insensitivity-can-cause-chaos/ How cp ends up being dangerous...! https://mfaani.com/posts/interviewing/how-to-think-recursively-part2/ Tue, 15 Nov 2022 16:46:46 -0500 https://mfaani.com/posts/interviewing/how-to-think-recursively-part2/ How to break down a recursive question into smaller pieces. Sophisticated Question. https://mfaani.com/posts/interviewing/how-to-think-recursively-part1/ Tue, 15 Nov 2022 13:15:37 -0400 https://mfaani.com/posts/interviewing/how-to-think-recursively-part1/ How to break down a recursive question into smaller pieces. Easy Question https://mfaani.com/posts/devtools/why-does-pod-lib-lint-fail-suddenly-fail-to-build/ Mon, 24 Oct 2022 10:57:20 -0400 https://mfaani.com/posts/devtools/why-does-pod-lib-lint-fail-suddenly-fail-to-build/ Why might pod lib lint fail to build while the app itself builds fine? https://mfaani.com/posts/interviewing/how-understanding-state-machines-helps-with-building-trees-and-graphs/ Thu, 06 Oct 2022 08:54:48 -0400 https://mfaani.com/posts/interviewing/how-understanding-state-machines-helps-with-building-trees-and-graphs/ A different way of seeing tree explorations https://mfaani.com/posts/training/what-resources-does-apple-provide-for-teaching-ios-to-students/ Wed, 21 Sep 2022 13:45:52 -0400 https://mfaani.com/posts/training/what-resources-does-apple-provide-for-teaching-ios-to-students/ Buried deep under Apple's K-12 resources? https://mfaani.com/posts/interviewing/arrays/which-way-am-i-sorting/ Wed, 03 Aug 2022 08:19:26 -0400 https://mfaani.com/posts/interviewing/arrays/which-way-am-i-sorting/ Ever confused as to what the end result of your sorting is? https://mfaani.com/posts/interviewing/recover-binary-tree/ Mon, 27 Jun 2022 09:29:51 -0400 https://mfaani.com/posts/interviewing/recover-binary-tree/ How do you fix a broken binary tree? https://mfaani.com/posts/interviewing/how-to-calculate-the-middle-index/ Sun, 19 Jun 2022 22:55:27 -0400 https://mfaani.com/posts/interviewing/how-to-calculate-the-middle-index/ Are middle indexes always actually the middle index? https://mfaani.com/posts/unicode-security/ Fri, 17 Jun 2022 00:06:40 -0400 https://mfaani.com/posts/unicode-security/ How Unicode can cause chaos https://mfaani.com/posts/interviewing/challenges/compress-string/ Wed, 15 Jun 2022 08:27:30 -0400 https://mfaani.com/posts/interviewing/challenges/compress-string/ Most simple compress algorithm https://mfaani.com/posts/interviewing/challenges/check-if-two-strings-are-one-edit-away/ Wed, 15 Jun 2022 06:26:52 -0400 https://mfaani.com/posts/interviewing/challenges/check-if-two-strings-are-one-edit-away/ Learn how to break down a question into smaller pieces https://mfaani.com/posts/interviewing/string/ Sun, 12 Jun 2022 14:49:48 -0400 https://mfaani.com/posts/interviewing/string/ Some discussion on Unicode and clustering and why converting a string to an array of characters makes things easier https://mfaani.com/posts/content-creation/how-to-prepare-yourself-as-a-podcast-guest/ Thu, 12 May 2022 05:10:04 -0400 https://mfaani.com/posts/content-creation/how-to-prepare-yourself-as-a-podcast-guest/ If you don't know anything about Podcasts, let alone how to be a guest on the show, then this post can get you in the right direction. https://mfaani.com/posts/what-is-a-self-contained-build-script/ Fri, 22 Apr 2022 13:11:12 -0400 https://mfaani.com/posts/what-is-a-self-contained-build-script/ Discussion about how to make your script work without interruption or manual intervention https://mfaani.com/posts/currentvaluesubject-example/ Thu, 14 Apr 2022 15:20:02 -0400 https://mfaani.com/posts/currentvaluesubject-example/ I googled a bit for “CurrentValueSubject Example”. Surprisingly I wasn’t able to find a simple answer. So I created a few examples: Basic import UIKit import Combine class ViewController: UIViewController { var name = CurrentValueSubject<String, Never>("Jason") override func viewDidLoad() { super.viewDidLoad() setup() } func setup() { let _ = name.sink { value in print(value) // Jason, Jason Bourne } name.send("Jason Bourne") } } Basically every time you call send on a publisher, the subscriber gets a callback. https://mfaani.com/posts/how-to-cherry-pick-a-library-fix/ Tue, 05 Apr 2022 12:22:16 -0400 https://mfaani.com/posts/how-to-cherry-pick-a-library-fix/ I’ve done this so many times, but every time I do it with hesitance. It’s usually because I’m not certain I’m finding the right commit or if I’m applying it the right way. These steps explain the process and how to validate that you’re doing thins the right way. Find out the library version that your release is using. Check out that version of your library. Create a new branch off that version. https://mfaani.com/posts/whats-the-difference-between-unowned-and-weak-references/ Fri, 11 Mar 2022 17:30:09 -0500 https://mfaani.com/posts/whats-the-difference-between-unowned-and-weak-references/ TIL I finally learned when to use unowned as opposed to using weak. Differences Under the hood: unowned is essentially a force-unwrap of a weak capture, with all that it entails. Because of this using it slightly more dangerous. Crash danger: Accessing an unowned reference while it’s nil will cause a crash. Compilation error: Every weak reference, must be an optional property. Otherwise you’ll get a compilation error: weak var delegate: DataEntryDelegate = DataHandler() // ERROR: 'weak' variable should have optional type 'DataEntryDelegate? https://mfaani.com/posts/how-fidelity-stocks-work/ Wed, 02 Mar 2022 21:50:44 -0500 https://mfaani.com/posts/how-fidelity-stocks-work/ I know this blog is mainly an engineering blog, but this is something I struggled to learn and thought blogging my findings would be helpful for my friends who want to learn about their investments or evaluate and compare offers. The following are a result of my findings after an hour long phone call with Fidelity representative. I opened the chat section in my browser and asked to speak with someone. https://mfaani.com/posts/uiapplication-backgroundtasks-through-the-lens-of-closures/ Tue, 22 Feb 2022 09:30:28 -0500 https://mfaani.com/posts/uiapplication-backgroundtasks-through-the-lens-of-closures/ 1 - The sync closure func processTwoNumbers(_ num1: Int, _ num2: Int, handler: (Int, Int) -> ()) { handler(num1, num2) } processTwoNumbers(10, 22, handler: { num1, num2 in print(num1 + num2) }) In the above, the handler is called in a sync matter. Same as below (1...100).forEach { val in print(val) } print(101) Uniqueness: The block passed in is executed immediately at the call site. 2 - The async closure — block isn’t stored. https://mfaani.com/posts/how-to-read-git-documentation/ Fri, 11 Feb 2022 08:55:15 -0500 https://mfaani.com/posts/how-to-read-git-documentation/ I was always perplexed with gits documentation. You need another documentation to just understand it. In this post I give tips on how to decipher it. https://mfaani.com/posts/what-is-manifest.lock-file/ Wed, 09 Feb 2022 06:47:16 -0500 https://mfaani.com/posts/what-is-manifest.lock-file/ In this post I discuss why there are two lockfiles and how that helps CocoaPods maintain integrity across machines https://mfaani.com/posts/what-is-uitransitionview-about/ Tue, 01 Feb 2022 14:21:03 -0500 https://mfaani.com/posts/what-is-uitransitionview-about/ I was using Xcode’s View Hierarchy and noticed this UITransitionView in my view hierarchy. ... UIWindow UITransitionView FooVC UITransitionView BarVC This was odd because I was expected a view hierarchy as such: ... UIWindow UITransitionView FooVC BarVC What made it more perplexing was that the canvas was showing things correct, but the View Hierarchy didn’t make sense. To be clear on jargon, the following is the name of each section of Apple’s view debugger: https://mfaani.com/posts/why-cant-xcode-show-caller/ Tue, 04 Jan 2022 22:26:19 -0500 https://mfaani.com/posts/why-cant-xcode-show-caller/ Edit Ever since I’ve upgraded to Xcode 16.1 I’ve experienced significant issues with finding callers. Yet aside from Xcode being broken, this post is still applicable for having a correct understanding of when / why / how Xcode should and shouldn’t work. Sample Project Download the sample project if you want. You don’t have to though. The project doesn’t even need to be ran. It’s just provided for context. I’m going to discuss two gotchas I hade with Xcode. https://mfaani.com/posts/swift-protocol-compile-time-check/ Thu, 30 Dec 2021 14:25:11 -0500 https://mfaani.com/posts/swift-protocol-compile-time-check/ I always thought that if you just use {get} on a protocol variable, then you can still set it i.e. it doesn’t matter if you give it a setter or not. That’s not true. It really depends on which compiler checks come in to place. Compiler checks are different depending on the type you want a variable to be. Can you guess which of the two snippets will compile? Snippet A https://mfaani.com/posts/ios/foreground-vs-background-runtime/ Mon, 01 Jan 0001 00:00:00 +0000 https://mfaani.com/posts/ios/foreground-vs-background-runtime/ https://mfaani.com/about/ Mon, 01 Jan 0001 00:00:00 +0000 https://mfaani.com/about/ I’m Mohammad Faani; I’m a husband, a father, local neighborhood friend and a software engineer