Blog by Jeevan

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Showing posts from November, 2018

Language Server Protocol (LSP) for Swift

You might already heard “ Apple announced LSP support for Swift ”. This is overwhelming decision by Apple because it’s a great step towards openness from it’s ‘monopoly game’. You can check complete official announcement here by Argyrios Kyrtzidis . What exactly LSP and How it works ? This Post from NSHipster by Matt explains how it works and what are the benefits out of the LSP support. In short, LSP will enable Swift development other than Xcode with below seamless integrated features - Autocompletion Jump to Definition Syntax highlighting Tooltips Automatic formatting and many for editor features. Any editor (say Visual Studio) to understand Swift, it requires Swift package to be integrated. Thus, SourceKit-LSP (Still under development) comes into play. This open source project got contribution from large group of developers and releasing very soon. Later we can easily integrate Swift into any editing tool with the help of any package manager (NodeJS prefer...

Stored Properties vs Computed Properties

We will start with simple a property which can be defined as below : var firstValue : Int let length : Int = 22 We can see it's not defined inside any closure, (A Closure "{ }" is meant for Classes, Structures or Enumerations) Stored Properties are those properties kept inside Classes and Structures. (not enums) . So, it will be always instance of classes or structures. Here is 2 more examples : struct FixedLengthRange { var firstValue : Int let length : Int } class FixedLengthRange { var firstValue : Int let length : Int } Computed properties are those properties which do not store values, instead it gives getter and optional setter methods to access those property values. struct Circle { var rad = 0 let pi = 3.14 var area : Float { get { return rad * rad * pi } ...

Implementing autocompletion OTP field in iOS

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...

Animating label text update - choosing a better way

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...

Cached Async Image in SwiftUI

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() { ...

Prevent Navigationbar or Tabbar overlapping Subview - solved for Card view

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...

UICollectionViewCell shows with wrong size on First time - Solved

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...