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Showing posts from November, 2025

Swift Optionals under the hood

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In Swift, an Optional is a way to say “this value might be there, or it might be missing.” We use ? to show that a value is optional, like: var name: String? But what is really happening behind the scenes? What an Optional Really Is Inside Swift, an Optional is just a simple enum with two cases: enum Optional<Wrapped> { case none // no value case some(Wrapped) // has a value } That’s all an Optional is! So when you write: var age: Int? Swift actually thinks: var age: Optional<Int> The ? is only a shortcut for us. Why Optionals Feel Special Even though Optionals are simple, Swift gives them extra features: if let and guard let value ?? defaultValue value! for force unwrap a?.b?.c for optional chaining These special features work only with Swift’s built-in Optional. How Swift Stores Optionals Swift stores Optionals in a smart way: Many Optionals take no extra memory compared to the normal value. Swift uses unused bits or adds a small...
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Understanding MVVM + Clean Architecture in SwiftUI

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When building an iOS app, it's important to organize your code in a way that keeps things clean, testable, and easy to maintain. One of the best ways to do that is by combining MVVM (Model–View–ViewModel) with Clean Architecture . 1. Presentation Layer — The SwiftUI Frontline This is where your app interacts with the user . In SwiftUI, the View and ViewModel live in this layer. View (SwiftUI View): These are your UI screens — for example, ContentView , LoginView , or ProfileView . SwiftUI Views are simple and reactive. They observe data and automatically update the UI when something changes. struct ContentView: View { @StateObject var viewModel = ContentViewModel() var body: some View { VStack { if viewModel.isLoading { ProgressView() } else { List(viewModel.items) { item in Text(item.title) } } } .onAppear { viewModel.fetchItems() } ...
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Understanding Task { }, Task.detached { }, and Task { @MainActor in … } in Swift Concurrency

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Swift’s concurrency model introduced a cleaner and safer alternative to GCD. But with this came a common confusion: When should I use Task {} , Task.detached {} , and Task { @MainActor in ... } ? If you’ve ever wondered which one to pick, this article will clear it up with simple explanations and real-world guidance.
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Popular posts from this blog

Implementing autocompletion OTP field in iOS

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Long waiting is over. !!  iOS 12 brings Autofill for OTP text field which is close to Android provided a decade back. Previously in iOS we used to toggle between OTP text screen and message inbox.  Which was hard to remember and time consuming resulting a bad user experience. Personally, I have been asked from the client/customer couple of times to implement autocompletion for OTP field and took me a lot of time to convey that it is not possible in iOS. Why Autofill was not possible previously?  We all know that Apple gives at most care for user privacy. When we see iOS architecture, each individual app is like a separate island. There is no inter-app bridge between apps (exception for Keychain and URLSchemes APIs which gives very limited scope). Thus we cannot read message content from inbox. Where to start Autofilling? First of all, the target SMS need to have the OTP Code with prefix string "Code" or "Passcode"on its message content. Beware of OTP c...
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Animating label text update - choosing a better way

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Recently I published a countdown app .  At one point of development - I have to show a timer on a UILabel which ticks on each seconds. As usual I started  setting text to a label object - self .timerLabel.text = someString Easy piece of cake right !?   But wait ... it won't take much user attention when timer ticks on every seconds. So I decided to make use of a simple animation while label gets text update. I found there are dozens of ways to animate a label. In this short article, I listed 3 best way you can animate text on a label. ( Spoiler Alert 👀- I decided to go with 3rd option)  1. Fade In - Fade out animation : CATransition class has got transition type `fade`. With timing function of CATransition - I was able to see the below result. let animation: CATransition = CATransition () animation.timingFunction = CAMediaTimingFunction (name: CAMediaTimingFunctionName .easeInEaseOut) animation.type = CATransitionType .fade animation.subtype = C...
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Cached Async Image in SwiftUI

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 SwiftUI’s AsyncImage is handy, but every time your view appears, it refetches the image—leading to flicker, delays, and unnecessary network use. What if you could fetch once, then reuse instantly? That's exactly what the Cached Async Image  delivers: a memory-powered caching layer that keeps SwiftUI image loading smooth, snappy, and resilient. First a simple in-memory cache without disk persistence. This will be thread-safe and auto-purges under memory pressure. A Singleton wrapping NSCache for URL → UIImage caching as follows : final class ImageCache {   static let shared = ImageCache()   private init() {}   private let cache = NSCache<NSURL, UIImage>()   func image(for url: URL) -> UIImage? {     cache.object(forKey: url as NSURL)   }   func insertImage(_ image: UIImage?, for url: URL) {     guard let image else { return }     cache.setObject(image, forKey: url as NSURL)   }   func clearAll() { ...
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Prevent Navigationbar or Tabbar overlapping Subview - solved for Card view

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Recently, I started with a Card view added as a subview of UIView in a view-controller. When a view controller created along subviews, it tends to use entire screen bounds and also slips behind Tab bar or Navigation bar. In my current situation, it's second case. Casually new iOS developers will write a patch by additional value for coordinate y and subtracting bar height from its size. A lot of them posted in SO threads too : How to prevent UINavigationBar from covering top of view? View got hidden below UINavigationBar iOS 7 Navigation Bar covers some part of view at Top So, how I got solved ? self.edgesForExtendedLayout = [] This  will avoid all subviews in a view controller get behind any bars. Read full apple  documentation on here. Full Source code below :  //Simple view controller where its view layed-out as a card. class WidgetCardViewController : UIViewController { var containerView = UIView () //MARK:- View Controller Life Cyc...
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UICollectionViewCell shows with wrong size on First time - Solved

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We commonly use Collection view where its cell size calculated run time. The flow layout delegate is responsible to return individual cell sizes. BUT in most of the cases, delegate method `collectionView: layout sizeForItem:` expects cell size too early. Before generating actual cell size. extension YourViewController : UICollectionViewDelegateFlowLayout { func collectionView ( _ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize { return CGSize (width: externalWidth, height: externalHeight) } } For instance, if a cell size depends on external view and its frame is not yet ready - results with wrong (or outdated) cell size. Typically happens for the first time view controller laid out all views. You can find similar queries in StackOverflow community : Collection view sizeForItemNotWorking UICollectionViewCell content wrong size on first load How to refresh UICollec...
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